PBS last night aired Frontline: League of Denial, an exhaustive examination of the NFL's history with concussion and other brain-related injuries (and its seemingly lackluster response to those issues). The hour-plus episode is the result of over 15 months of investigative work, though it's based on a book by ESPN reporters Mark Fainaru-Wada and Steve Fainaru. PBS and ESPN had originally agreed to collaborate on the project, but ESPN abruptly dropped out back in August. The sports network asked that PBS not use its logos or give ESPN any collaborative credit on the program. PBS carried on undeterred with the help of both reporters, finally airing the eye-opening special last night. Frontline paints a troubling portrait of a league that has long been aware of the threat concussions pose to its players, but one that has been relatively slow in addressing the safety crisis.

For their part, Frontline's producers don't seem to be finished with the issue just yet; they've set up a Concussion Watch tracker that's been aggregating head injuries throughout the 2013 NFL season. Safety aside, it's also proven to be an expensive problem for the NFL; earlier this year the league reached a $765 million settlement with 4,500 players who accused the NFL both of not doing enough to protect them, and underplaying the threat of concussions to players and the public at large. Today at 1:00PM ET, viewers can join a live chat with Frontline producer Mike Wiser, reporters Steve Fainaru and Mark Fainaru-Wada, and Richard Deitsch of Sports Illustrated.