I'm unable to watch football these days as I used to. I desperately wish I could, but I just can't. And after you finish reading this book, you won't be able to either.

The book is League of Denial, from brothers Mark Fainaru-Wada (co-author of Game of Shadows) and Steve Fainaru (2008 recipient of the Pulitzer Prize for international reporting), and it is one that the National Football League probably wishes was never written. The book explores the football factory that was the city of Pittsburgh, why it became the epicenter of the NFL's concussion crisis, and how an improbable character by chance flicked the first domino to set off a devastating chain reaction with which the league is still grappling. Since assisting these two ESPN investigative reporters with research on their book, I've replaced my weekly excitement waking up in anticipation of an autumn Sunday morning filled with football to one of mostly disgust.

Early on in League of Denial, we are introduced to Mike Webster, the Hall of Fame center and linchpin for the dominant Steelers teams of the 1970s and early '80s that won four Super Bowls. "Iron Mike," as he was known, was a fan favorite because, dating back to his modest, workman-like Midwestern upbringing, he absolutely epitomized the hardhat population that made up the blue-collar community of the era. He went on to became a nine-time Pro Bowler and five-time First-Team All-Pro, at one point after a contest was held even owned the title of "The Strongest Man in Football," and is unquestionably one of the greatest to ever play professionally.

The problem, however, was upon Webster's retirement in 1990 at the age of 38 following two final seasons with the Chiefs, his wife and children immediately noticed a serious change in him. After building what the family thought was their dream home in Kansas City, Webster rapidly transformed into less and less the man they knew and loved. He would suddenly disappear for weeks on end, miss important family events and school functions, often sleep in his pickup during his mysterious sojourns or in bus and train stations along the way, and began to require myriad prescription drugs to even function on a day-to-day basis.

Just a few years later, Webster and his family were unexplainably in financial ruin, his health was quickly deteriorating and his mind was perhaps going even faster. The former strongman and anchor of the Steelers powerful offense was only in his 40s, but in the shocking physical and mental condition of applying duct tape to deep, unhealing cracks in his feet as if it were bandages, employing a stun gun to knock himself unconscious in order to sleep, and using Super Glue to reattach the teeth that began falling out of his head. No one could quite understand what happened to the man who had previously almost never left the football field because of injury. The doctors who examined him feared brain damage from his 17 years of professional ball, but the NFL refused to acknowledge any correlation, until its retirement board finally granted him a pittance late in his life. In 2002, 12 years after retiring, and at just 50 years old, he was dead.

Enter Bennet Omalu, a junior staffer at a Pittsburgh county coroner's office—perhaps the unlikeliest of figures to uncover the NFL's festering predicament. The Nigerian-born pathologist was fresh out of school at the University of Pittsburgh Medical Center and happened to dissect Webster's body. Knowing almost nothing of football, he had the random foresight to examine the Steeler legend's brain. What he found, that Webster showed obvious signs of degeneration, likely from repeated head trauma—a disease he would formally name chronic traumatic encephalopathy (CTE)—quickly put the NFL on the defensive. They actively pushed outlandish scientific declaration and corporate mitigation to offset scrutiny that might otherwise have helped make the game safer.

"It really was a systematic campaign that went on for nearly two decades to really downplay the seriousness of this injury," co-author Steve Fainaru told me last week, "while at the same time there was a growing body of research that strongly suggested that the opposite was true. They didn't really ultimately alter their policies until they were at the point of a legal bayonet and under pressure from Congress."

The NFL did its best to discredit and marginalize Omalu's discovery. "The league used its economic, political, and media power to attack pioneering research and try to replace it with its own," the authors write. Yet independent study after independent study yielded the same results and startled those who probed Omalu's findings after they personally analyzed the brash and eccentric forensic neuropathologist's research.

Years earlier, the league, under the leadership of Commissioner Paul Tagliabue, refused to even accept that concussions were a problem within the league, let alone research starting to show that, like boxers before them, football players were showing signs of steep mental decline from repeated knocks to the head. Tagliabue had been known to refer to this impending football epidemic as "a pack journalism issue." In the meantime, repeated and untreated concussions in former players were accelerating their descent into Alzheimer's, Parkinson's, and dementia.

Under mounting pressure from the media and increasing concern within the medical community, the NFL established the Mild Traumatic Brain Injury Committee in 1994. Tagliabue, curiously, appointed Jets team doctor Elliot Pellman, a rheumatologist who had not previously written a single page of scientific literature on concussions, as the committee's chairman.

"Quite frankly it was comical the way in which the original committee was pulled together; comical is probably the nicest way I could describe it," Kevin Guskiewicz, one of the leading experts in the field of sports-related concussions, and now a member of the NFL's newly christened Head, Neck and Spine Committee, says in the book.

Pellman's lack of background in the field didn't stop him from publishing, as the lead author on behalf of the league, 16 separate scientific papers refuting the link between concussions and long-term neurological decay. Among the beliefs continually asserted was the statistical occurrence of just one total concussion among all players every three or so games. "Professional football players do not sustain frequent repetitive blows to the brain on a regular basis," the committee wrote in one study, and "it is unlikely that athletes who rise to the level of the NFL are concussion prone," in another. And in yet one more, "many NFL players can be safely allowed to return to play on the day of injury after sustaining an MTBI." "Concussions," Pellman told Sports Illustrated in 1994, "are part of the profession, an occupational risk."

While Pellman stepped down from the NFL's committee focused on concussions in 2007, he remains employed by the league, officially bestowed the title of "NFL Medical Director," although what his role is no one outside of the league seems to understand. Nevertheless, to this day, the NFL has only ever once publicly conceded the connection between concussions and latent brain issues. In December 2009, when contacted by The New York Times' reporter Alan Schwarz, NFL spokesman Greg Aiello stated, "It's quite obvious from the medical research that's been done that concussions can lead to long-term problems. We all share the same interest. That's as much as I'm going to say." This, of course, contradicted years of NFL statements, and there has been nary a peep since. The league recently reached a settlement worth upwards of $1 billion with more than 4,500 former players who sued over negligence. The agreement does not require the NFL to admit any fault in the players' injuries, and those who represent the league repeatedly declined to assist in the reporting of the book.

"Frankly, I don't think they did themselves a big favor because the information that we were able to gather was not flattering to the NFL, I mean, obviously," Fainaru told me. "There's a lot of nuance around the science, that even now there's a lot of disagreement around the science and I think it would have been really helpful for people with the NFL to talk to us and provide us their views on why they came to these conclusions. We tried, and I would have loved for the NFL to have cooperated, but I don't think really anybody was served by that—particularly the NFL—by not cooperating."

The book goes on to document how the NFL repudiated its earlier neglectful attitude toward the issue of concussions, donated money to various brain studies and research institutions well after the fact, and deflected attention away from its emphasis on the aggression and violence that made the sport the multibillion-dollar operation it is today. All the while the NFL maintained a retirement board that went to great lengths to prevent former players from completing valid neurological-based claims—and in so doing, basically waiting out the health of those most in need.

By the end of my work on the book, I found myself unable to ignore the fundamental conundrum that still remains at the heart of professional football—that the inherent brutality of the game has a real toll on its players, destroying many of their lives. After reading it, you will not watch a game the same way ever again.