Though Garcia is often remembered as Captain Trips, the avuncular psychedelic cheerleader, Mr. Bar-Lev locates in him something darker and lonelier. As he is portrayed in the early parts of the film, Garcia is a man of irrepressible, joyful charisma. It is painful to watch his inexorable decay as the enormity of the Grateful Dead enterprise pushes him toward the solace of heroin addiction and, ultimately, his death from a heart attack when he was 53.

“I feel like Jerry was always keeping an eye on his future nonbeing from a very young age, and that’s one of the very useful things about the Grateful Dead, it’s a meditation on death,” Mr. Bar-Lev said. “The more you think about death, the more committed you become to living in the moment. So it’s not accidental that he has this effusive, vibrant life force and also embodies a certain inevitable march towards death. That’s the heart of the Grateful Dead. That’s why the two icons are the rose and the skull.”

Mr. Bar-Lev initially approached the Dead organization in 2003 with the idea of making a film about the band’s lyrics. He got a quick go-ahead and a blessing from Alan Trist, a longtime Dead employee who then ran the band’s publishing operation and is a significant presence in the film. “I did a back flip,” Mr. Bar Lev said. “I couldn’t believe it was that easy. But it wasn’t easy.”

It wasn’t until 2015, the band’s 50th anniversary, that he finally gained the cooperation he had sought a dozen years before and was commissioned to make a 90-minute film. All four of the band’s surviving members — Bob Weir, Phil Lesh, Bill Kreutzmann and Mickey Hart — agreed to appear on film. He was also given full access to the band’s voluminous archives, which created its own set of challenges. To process the material, he had to create what he called “a costly apparatus” to sift through and log thousands of photographs — more than 1,100 appear in the finished documentary — hours of film footage and hundreds of interviews the band members gave over the years.

It didn’t take long to realize that it would be impossible to fulfill his original assignment. “We got to 1974, and it was already two hours long,” Mr. Bar-Lev said. At some points, he seemed on the verge of getting lost in the material.