That moment came around the time when Robin went to Los Angeles to start working on The Crazy Ones. “I’m kicking myself for not visiting him during that time,” Zak said. “Because I think that was a very lonely period for him. In retrospect, I feel like I should have been there, spending time with him. Because someone who needs support was not getting the support he needed.”

Throughout this time, Robin’s son Zak was often in contact with Robin’s longtime assistant Rebecca Erwin Spencer and her husband, Dan, who lived in Corte Madera, near Tiburon, and who Zak felt took good care of Robin. “They were very open and did love him very much—they were pretty good about keeping us in the fold,” he said. “I think there was inclusivity up until a point when things started getting a little weird.”

During the making of The Crazy Ones, Robin lived in Los Angeles, by himself, in a modestly furnished rental apartment. It was a far cry from when he last starred in a Hollywood sitcom, and an even more scaled-down existence than he had established for himself in Tiburon. Robin’s new domestic life with his wife, Susan, was very different, too. Unlike his ex-wife Marsha, who saw it as her responsibility to decorate and maintain their house, to organize dinner parties and surround him with intellectual friends who kept him stimulated, Susan had been accustomed to living an independent life of her own. She traveled widely by herself and with her sons, and she did not manage Robin’s day-to-day affairs and did not always accompany him when he worked out of town.

The ratings foretold a bleak outlook: the first episode of The Crazy Ones was watched by about 15.5 million people, a respectable start that suggested at least a curiosity about the series. But within a month, nearly half that audience had tuned out, and the numbers eroded further with each passing week. It was no Mork & Mindy; the magic was gone.

Some critics, at least, were gentle in noting that the Robin of The Crazy Ones was no longer the indefatigable dynamo they had come to adore in an earlier era. Others were not so diplomatic, like the one who simply wrote, “Williams seems exhausted. So is this show.”

When the first episode of The Crazy Ones aired on September 26, it was met with lukewarm reviews. Unlike Mork & Mindy, which had been filmed in front of a live studio audience that responded to his every ad-lib with uproarious laughter, The Crazy Ones used a single-camera format that was a poor fit for Robin’s talents. The show played like a movie running in an empty theater, and each joke hung awkwardly in the air as it was met with silence.

But there was an even simpler pleasure about The Crazy Ones. As Robin explained, “It’s a regular job. Day to day, you go to the plant, you put your punch card in, you get out. That’s a good job.”

The Crazy Ones seemed perfectly calibrated for the older audience cultivated by CBS, which had a track record for giving new lifeblood to bygone TV stars, while the show provided Robin with distinct opportunities to improvise in each episode. It surrounded him with an ensemble of young actors, who helped to offset the fact that Robin was now gaunter and grayer than viewers were accustomed to seeing, and it paid a steady salary of $165,000 an episode—more in a week than he’d earn in a month working for scale on an independent movie.

Robin continued to bounce from one low-budget film to the next. But he finally seemed poised for a professional resurgence when he was cast in The Crazy Ones, a new CBS comedy show that would make its debut in September 2013. The series was Robin’s first ongoing television role since Mork & Mindy ended three decades earlier, casting him as Simon Roberts, the irrepressible, not yet over-the-hill co-founder of a fast-paced Chicago advertising agency he runs with his straitlaced daughter ( Sarah Michelle Gellar ).

So why did Robin persist in making these films, each one a far cry from the Hollywood features he had once thrived on, and which were lucky to receive even a theatrical release? Why did he continue to fill every free block of time in his schedule with work, whatever work he could find? Yes, he needed the money, especially now that he had two ex-wives and a new spouse he wanted to provide with a comfortable home. “There are bills to pay,” he said. “My life has downsized, in a good way. I’m selling the ranch up in Napa. I just can’t afford it anymore.” He hadn’t lost all his money, but, he said, “Lost enough. Divorce is expensive.”

Later that fall, Robin was in New York making a film called The Angriest Man in Brooklyn, another morbid indie comedy, in which he plays its title character, a surly lawyer who is diagnosed with an aneurysm and told he has 90 minutes to live. In one scene, the character jumps off the Brooklyn Bridge into the East River, but he survives, and he is dragged from the water by the doctor who, it turns out, has falsely diagnosed him. When he described the creation of this sequence to David Letterman, the host had asked him if he needed a gamma-globulin shot, and Robin answered, “I didn’t get a shot, and I hope it doesn’t end up, 20 years from now, I’m not like Katharine Hepburn, going, [quavering voice] ‘E-very-thing’s fi-ine.’”

The work was less abundant than it used to be and nowhere near as lucrative, and so much of it seemed to be focused on finality, particularly in the form of death. In August 2012, he had appeared in an episode of Louie, the cable-TV comedy written by and starring the comedian Louis C.K., that begins with both men meeting at the grave of a comedy-club manager who has recently died, and whom they both privately despised. “When he died, I felt nothing,” Louie tells Robin. “I didn’t care. But I knew—when I pictured him going in the ground and nobody’s there, he’s alone, it gave me nightmares.” Robin replies, “Me too.”

What did he still get out of doing what he was doing, and why did he feel the compulsion to keep doing it? He had already enjoyed nearly all of the accomplishments that one could hope for in his field, tasted the richest successes, won most of the major awards. Every stage of his career had been an adventure into the unknown, an improvisation in its own right, but there was truly no road map for where he was now. Everything came to an end at some point; it was a reality he accepted and confronted so often in his work, even as he tried to out-race it. What would it look like for him, he wondered, when he wrapped things up and told the crowd good night for the last time? How could it be anything other than devastating?

It was a question that crossed Robin’s mind more often these days, now that he had put in roughly 35 years as a professional entertainer and more than 60 as a human being.

Here, Itzkoff traces the last few months of Williams’s life. His reporting draws on the perspectives of some of Williams’s closest confidants and family members, including Billy Crystal ; his Mork & Mindy co-star Pam Dawber ; his oldest son, Zak Williams; his daughter-in-law, Alex Mallick-Williams ; his makeup artist, Cheri Minns ; and his old friends Mark Pitta, Cyndi McHale, and Wendy Asher. Robin is available May 15.

Meanwhile, Williams was also reeling from a cataclysmic diagnosis: in May 2014, he had been told that he had Parkinson’s disease, news that stunned and overwhelmed the once-nimble comedian. Even more crushing than this is the possibility that Williams was misdiagnosed; an autopsy would later reveal that he actually had Lewy body dementia, an aggressive and incurable brain disorder that has an associated risk of suicide.

Robin Williams’s August 2014 suicide was devastating to those who knew him best—and it also came at the end of a long and difficult decline, as this excerpt from New York Times culture reporter Dave Itzkoff’s new biography, Robin , demonstrates. In the months that preceded his death, Williams faced daunting challenges, both professionally and personally. His film career had stalled, and his comeback sitcom, The Crazy Ones, was failing to find an audience on CBS. He was still harboring guilt about his divorce from Marsha Garces, his second wife and mother of two of his children, and adjusting to life with his new wife, Susan Schneider, whom he married in 2011.

Starting in October 2013, Robin began to experience a series of physical ailments, varying in their severity and seemingly unconnected to one another. He had stomach cramps, indigestion, and constipation. He had trouble seeing; he had trouble urinating; he had trouble sleeping. The tremors in his left arm had returned, accompanied by the symptoms of cogwheel rigidity, where the limb would inexplicably stop itself at certain fixed points in its range of motion. His voice had diminished, his posture was stooped, and at times he simply seemed to freeze where he stood.

Susan was used to seeing Robin experience a certain amount of nervousness, but when she spoke to him now, his anxiety levels seemed off the chart. “It was like this endless parade of symptoms, and not all of them would raise their head at once,” she said. “It was like playing whack-a-mole. Which symptom is it this month? I thought, is my husband a hypochondriac? We’re chasing it and there’s no answers, and by now we’d tried everything.”

Billy Crystal said that Robin began to reveal some of his discomfort, but only up to a point. “He wasn’t feeling well, but he didn’t let on to me all that was going on,” Crystal said. “As he would say to me, ‘I’m a little crispy.’ I didn’t know what was happening, except he wasn’t happy.”

In the fall, Crystal and his wife, Janice, invited Robin out to see the Joseph Gordon-Levitt comedy Don Jon at a movie theater in Los Angeles. When they met at the parking lot, Crystal said, “I hadn’t seen him in about four or five months at the time, and when he got out of the car I was a little taken aback by how he looked. He was thinner and he seemed a little frail.”

Over dinner afterward, Crystal said, “He seemed quiet. On occasion, he’d just reach out and hold my shoulder and look at me like he wanted to say something.” When the friends said goodbye at the end of the night, Robin burst out with unexpected affection. “He hugged me goodbye, and Janice, and he started crying,” Crystal said.“I said, ‘What’s the matter?’ He said, ‘Oh, I’m just so happy to see you. It’s been too long. You know I love you.’”

On their car ride home, Crystal said he and Janice were barraged by calls from Robin, sounding tentative and expressing his appreciation for the couple. “Everything’s fine, I just love you so much, ’bye,” went one call. Five minutes later the phone rang again: “Did I get too sappy? Let’s see each other soon.”

From BEI/REX/Shutterstock.

Before production wrapped on The Crazy Ones in February 2014, its producers made a last-ditch effort to re-invigorate its viewership with a bit of guest casting. Pam Dawber was invited to play a role in one episode, as a possible romantic interest for the Simon Roberts character, marking the first time that she and Robin had performed together since Mork & Mindy, and the first screen role that Dawber—who had stepped back from the business to raise her children with the actor Mark Harmon—had taken in 14 years.

Dawber knew the stunt was something that would only be attempted by a TV series faced with the looming threat of cancellation, but she accepted the role anyway. “I did that show only because I wanted to see Robin,” she said. “Not because I thought it was a great show. I thought it was such the wrong show for Robin, and he was working as hard as he could. The couple episodes I saw, I felt so sorry for him, because he was just sweating bullets. He was sweet and wonderful and loving and sensitive. But I would come home and say to my husband, ‘Something’s wrong. He’s flat. He’s lost the spark. I don’t know what it is.’”

Dawber also drew the conclusion that Robin was experiencing serious health problems, but she felt uncomfortable broaching the subject with him. “In general, he was so not who I knew him to be,” she said. “But I didn’t feel right prying, because I hadn’t been around him. So I did what I could. ‘I hear you have a new marriage.’ ‘Oh, she’s wonderful. She’s so sweet.’”

Despite its retro-TV reunion hook and the increased promotion it received, Dawber’s episode of The Crazy Ones did nothing to stop the show’s continued ratings slide. The next week, its season finale was watched by barely five million people. The following month, CBS canceled the show. Friends like Mark Pitta, who spoke to Robin during this period, believed he was at peace with the network’s decision. “I said to him, ‘How are you doing?’” Pitta recalled. “And he just volunteered it. He goes, ‘Well, my show was canceled.’ I said, ‘How’s that going for you?’ He goes, ‘Well, bad financially. Good creatively.’”

By that time, Robin had already moved on to filming Night at the Museum: Secret of the Tomb, the third film in the family-comedy franchise. That previous winter, he had shot a portion of the movie in London, and now he was completing the rest of his scenes in Vancouver. Though it was the first big-budget feature that Robin had worked on in some time, it was a project that many people close to him had hoped he would not take—it was clear to them that whatever had been afflicting him was getting worse, and he needed to push the pause button on his career until his mystery illness was brought under control.

But what proved more powerful than the pleas from his colleagues and from family members to slow things down—even more powerful than Robin’s desire to sustain his life with Susan and to be a good earner for his managers and agents—was his own desire to keep working through the pain, the one cure-all that had helped him cope with past troubles.

“I don’t think he thought he could blow up what he built for himself,” Cheri Minns, his makeup artist, said. “It’s like he didn’t worry about anything when he worked all the time. He operated on working. That was the true love of his life. Above his children, above everything. If he wasn’t working, he was a shell of himself. And when he worked, it was like a light bulb was turned on.”

By the time he reached Vancouver, Robin’s weight loss was severe and his motor impairments were growing harder to disguise. Even his once-prodigious memory was rebelling against him; he was having difficulty remembering his lines.

“He wasn’t in good shape at all,” Minns said. “He was sobbing in my arms at the end of every day. It was horrible. Horrible. But I just didn’t know.”

Robin was no longer leaving his hotel room at night, and in April he suffered a panic attack. Minns thought that maybe if he slipped out to a local Vancouver comedy club and performed again, it would lift Robin’s spirits and remind him that audiences still loved him. But instead, her gentle suggestion had a devastating effect. “I said, ‘Robin, why don’t you go and do stand-up?’” she recalled. Robin broke down in tears. “He just cried and said, ‘I can’t, Cheri.’ I said, ‘What do you mean, you can’t?’ He said, ‘I don’t know how anymore. I don’t know how to be funny.’ And it was just gut-wrenching to hear him admit that, rather than lie to me and say something else. I think that’s how troubled he was about all of it.”

Susan had remained in California while Robin worked on the movie, but she was in frequent contact with him, too, talking him through his escalating insecurities. Under the supervision of his doctor, Robin started taking different anti-psychotic medications, but each prescription only seemed to alleviate some symptoms while making others worse. When Robin finished his work on Night at the Museum and returned home to Tiburon in early May, Susan said her husband was “like a 747 airplane coming in with no landing gear.”

“Robin was losing his mind and he was aware of it,” she said. Susan said that Robin told her he wanted a “reboot for his brain,” but he was stuck in a looping paranoia that would spin around and around in his mind. Every time it seemed as if he had been talked down from the latest obsession, he returned to it all over again, fresh in his mind, as if he were encountering it for the first time.

A few days after he came back from Vancouver, Robin was stirred from a fitful evening of sleep, gripped by the certainty that some grave harm was going to befall Mort Sahl. He kept wanting to drive over to Sahl’s apartment in Mill Valley to check on him and make sure he was safe, while Susan had to repeatedly convince him that his friend was not in any danger. They went over it, again and again and again, all night, until they both finally fell asleep at 3:30 that morning.

On May 28, 2014, Robin was finally given an explanation for the tangled lattice of sicknesses that had been plaguing him. He was diagnosed with Parkinson’s disease, a degenerative disorder that attacks the central nervous system, impairing motor functions and cognition, eventually leading to death. To Robin, it was the realization of one of his most deeply felt and lifelong fears, to be told that he had an illness that would rob him of his faculties, by small, imperceptible increments every day, that would hollow him out and leave behind a depleted husk of a human being. Susan tried to find some small shred of positivity in the ordeal—at least now Robin knew what he had and could focus on treating it. “We had an answer,” she said. “My heart swelled with hope. But somehow I knew Robin was not buying it.”

Robin shared the news of his Parkinson’s diagnosis with his innermost circle: with his children, with his professional handlers, and with his most intimate friends. Crystal recounted the conversation in which Robin revealed the devastating news to him. “His number comes up on my phone,” he said, “and he says, ‘Hey, Bill.’ His voice was high-pitched. ‘I’ve just been diagnosed with Parkinson’s.’ I didn’t miss a beat. Because of my relationship with Muhammad Ali, I knew a lot of really good Parkinson’s research doctors. I said, ‘In Phoenix, the research center is great. If you want, we can get you in there. It would be totally anonymous. Do you want me to pursue that?’ ‘Would you?’”

“I never heard him afraid like that before,” Crystal said. “This was the boldest comedian I ever met—the boldest artist I ever met. But this was just a scared man.”

Among his associates who knew, there was unease: they were worried, of course, about Robin’s well-being, but also concerned about whether he was in a position to receive the assistance he needed. “I don’t think the people around him knew how to handle it and how to help him,” Cyndi McHale said. “Look, it’s the perfect storm. He had a physical condition that was manifesting. He knew there was something wrong with his brain. And two of his best friends—my late husband and Christopher Reeve—ended up paralyzed in a wheelchair. So he’s thinking, O.K., I’m losing control of my body. There’s something going on in my brain. I think he was just trapped.”

Robin’s children felt that it was now more important than ever to share time with their father. But doing so meant navigating past layer after layer of other people who also had access to him and wanted his attention—Susan; his assistant, Rebecca; his managers—and even this much resistance could discourage them from seeking him out.

When Robin did have time to get together with him, Zak could tell that his father was in anguish, and not only from the strain of his condition. “It was really difficult to see someone suffering so silently,” Zak said. “But I think that there were a series of things that stacked, that led to an environment that he felt was one of pain, internal anguish, and one that he couldn’t get out of. And the challenge in engaging with him when he was in that mind-set was that he could be soothed, but it’s really hard when you then go back into an environment of isolation. Isolation is not good for Dad and people like him. It’s actually terrible.”

Robin’s children had always been a dependable source of some of the purest, most natural joy he had experienced. But when he saw them now, they were also a reminder that he had chosen to end his marriage to Marsha and break up their home; it filled him with shame to think that he had inflicted the divorce upon them, and the shame compounded itself as he came to believe he had taken something perfect and corrupted it.

Even when his children told him that he had no reason to hold on to his guilt and nothing to apologize for, Zak said, “He couldn’t hear it. He could never hear it. And he wasn’t able to accept it. He was firm in his conviction that he was letting us down. And that was sad because we all loved him so much and just wanted him to be happy.”

At home, Susan saw Robin’s condition continue to worsen. When they tried to sleep at night, Robin would thrash around the bed, or more often he would be awake and wanting to talk about whatever new delusion his mind had conjured up. Robin tried many treatments to regain the upper hand over the disease: he continued to see a therapist, work out with a physical trainer, and ride his bike; he even found a specialist at Stanford University who taught him self-hypnosis. But each of these strategies could only do so much. In the meantime, Robin started sleeping in a separate bedroom from Susan.

Robin’s longtime friend Eric Idle, who was in London that summer preparing for a Monty Python reunion show, tried unsuccessfully to persuade Robin to fly out there and make a cameo appearance at one of the performances. “And all the time I was getting e-mails from him, and he was going downhill,” Idle recalled. “Then he said he could come, but he didn’t want to be onstage. I said, ‘I totally get that.’ Because he was suffering from severe depression.” Through their mutual friend Bobcat Goldthwait, Idle said, “We were in touch, and in the end he said, ‘I can’t come, I’m sorry, but I love you very much.’ We realized afterwards he was saying goodbye.”

In June, Robin checked himself into the Dan Anderson Renewal Center in Center City, Minnesota, another Hazelden addiction treatment facility like the one where he had been treated in Oregon in 2006. Publicly, his press representatives said that he was “simply taking the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud.” In fact, this rehab stay was Robin and Susan’s understandably inelegant fix for a problem that had no solution. At the very least, it kept Robin cloistered on a campus where he could receive close supervision, and where he could meditate, do yoga, and focus on further 12-step work that, it was hoped, would help him manage his illness.

But other friends felt that Robin had no reason to stay at a clinic for drug and alcohol rehabilitation when he was suffering from an unrelated physical disorder. “That was wrong,” said Wendy Asher. “Robin was drinking when he went to rehab, and this wasn’t that. This was a medical problem. Susan thought everything would be fixed through A.A., and it just wasn’t true.”

July 21 was Robin’s 63rd birthday, but few of his friends seemed able to reach him and offer their warm wishes on the day. Cyndi McHale, who had the same birth date as Robin and had a regular tradition of speaking to him on the day, could not track him down; “I was on the phone with his managers’ assistant,” she said, “and she was just like, ‘He’s not doing well.’ That was a common line. Rebecca was just like, ‘No, he’s not doing well.’ I was really worried about him.” McHale had not seen Robin, either, at a recent birthday party for George Lucas, an event that he reliably attended. “When he didn’t go to that,” she said, “I thought, uh-oh, it’s really much worse than anybody is letting on.”

On the morning of July 24, Susan was taking a shower when she saw Robin at the bathroom sink, staring intensely at his reflection in the mirror. Looking more carefully at him, she noticed that Robin had a deep cut on his head, which he occasionally wiped at with a hand towel that had become soaked with blood. She realized that Robin had banged his head on the wooden bathroom door and began to scream at him, “Robin, what did you do? What happened?” He answered, “I miscalculated.”

“He was angry because by now he was so mad at himself for what his body was doing, for what his mind was doing,” Susan later explained. “He would sometimes now start standing and being in trance-like states and frozen. He had just done that with me and he was so upset. He was so upset.”

The last time that Mark Pitta saw Robin at the Throckmorton Theatre was at the end of July, and the encounter left him cold. “I was scared,” Pitta said, “because it wasn’t my friend. I said, this has nothing to do with his TV show being canceled. He had a thousand-yard stare going. I just talked to him, I said, ‘Man, you’re not going to believe this. Somebody ran over my cat, 20 feet in front of my house.’ And Robin had absolutely no reaction, at all. I was like, uh-oh.”

Later in the theater’s greenroom, Pitta and Robin were mingling with another comedian who had brought his service dog. As Pitta recounted the scene, “I just casually said, ‘Another comedian I know has a service dog. The dog wakes her up when she chokes in her sleep.’ And Robin instantly said, ‘Oh, a Heimlich retriever.’ It got a huge laugh. He just sat there and had a little smile on his face.” When he and Robin left the theater at the end of the evening, Pitta said, “I gave him a hug and I said goodbye. He said goodbye to me three times that night. And he said it exactly the same way. He goes, ‘Take care, Marky.’ He said it three times.”

One evening in early August, Robin made one of his intermittent visits to Zak and Alex’s house in San Francisco, as he did when Susan was out of town. This time she happened to be in Lake Tahoe, and Robin showed up to see his son and daughter-in-law like a meek teenager who realizes he’s stayed out past his curfew; he was always welcome there, but he carried himself with mild discomfort, as if he still needed someone else’s permission to be in their home. At the end of the night, as Robin was preparing to head back to Tiburon, Zak and Alex asked him what it would take to keep him at their house—would they have to tie him up and throw a bag over him?

“Well, that was a joke,” Zak said with a bittersweet laugh. “To be clear, that was a joke. But we didn’t want someone who seemed like he was in so much anguish to leave. We wanted him to stay with us. We wanted to take care of him.”

On the night of August 10, a Sunday, Robin and Susan were home together in Tiburon when Robin began to fixate on some of the designer wristwatches that he owned and grew fearful that they were in danger of being stolen. He took several of them and stuffed them in a sock, and, at around 7 P.M., he drove over to Rebecca and Dan Spencer’s house in Corte Madera, about two and a half miles away, to give them the watches for safekeeping. After Robin came home, Susan started getting ready for bed; he affectionately offered her a foot massage, but on this night, she said she was O.K. and thanked him anyway. “As we always did, we said to each other, ‘Good night, my love,’ ” Susan recalled.

Robin went in and out of their bedroom several times, rummaged through its closet, and eventually left with an iPad to do some reading, which Susan interpreted as a good sign; it had been months since she’d seen him read or even watch TV. “He seemed like he was doing better, like he was on the path of something,” she later said. “I’m thinking, ‘O.K., stuff is working. The medication, he’s getting sleep.’” She saw him leave the room at around 10:30 P.M. and head to the separate bedroom he slept in, which was down a long hallway on the opposite side of their house.

When Susan woke up the next morning, Monday, August 11, she noticed that the door to Robin’s bedroom was still closed, but she felt relieved that he was finally getting some needed rest. Rebecca and Dan came over to the house, and Rebecca asked how the weekend had gone with Robin; Susan optimistically answered, “I think he’s getting better.” Susan had been planning to wait for Robin to wake up so that she could meditate with him, but when he wasn’t awake by 10:30 A.M., she left the house to run some errands.

By 11 A.M., Rebecca and Dan were concerned that Robin still had not come out of his room. Rebecca slipped a note under the door of Robin’s bedroom to ask if he was O.K. but received no response. At 11:42 A.M., Rebecca texted Susan to say she was going to wake Robin up, and Dan went to find a step stool to try to look through his bedroom window from the outside of the house. In the meantime, Rebecca used a paper clip to force open the lock to the bedroom door. She entered the room and made a horrifying discovery: Robin had hanged himself with a belt and was dead.

Excerpted from Robin by Dave Itzkoff. Published by arrangement with Henry Holt and Company, May 15, 2018. Copyright © 2018 by Dave Itzkoff. All rights reserved.