Academy Award® winning Director Alex Gibney takes an unprecedented look at the National Hockey League’s most feared enforcers and explores the career of Chris "Knuckles" Nilan. The role was simple: protect their teammates no matter the cost. For Chris this meant a shattered body, addiction to drugs, and harming the people closest to him. But in the process, he won the love of hockey’s holy city, Montreal, and helped the team win the Stanley Cup. Through interviews with hockey’s toughest guys, the film explores what it means to enforce the unspoken code of the NHL.