Legendary documentarian Steve James (Hoop Dreams) again turns his camera on the dark side of America's obsession with sports, this time looking at the rash of suicides and dementia linked to concussions. He opens with the charismatic Chris Nowinski, a Harvard grad-turned-pro wrestler who made a second career investigating the effects of head injuries sustained in sports. "When I hear about these [athletes dying], it's my job to get their brain," he states with a mixture of obligation and dread. One wishes James stuck with Nowinski for the whole film, rather than going with an episodic construction (we also look at pro hockey and women's soccer, among other things) that feels destined for PBS. Still, all it takes is a few moments with the next generation to see the gravity of the problem. Seeing former NHL star Keith Primeau's teenage son light up to talk about how fighting is "pretty fun" gives us the conclusion the statistics can't yet provide: before the games can change, we need to.