True story: Forensic neuropathologist Dr. Bennett Omalu, a Nigerian immigrant to the USA, discovered a type of brain trauma caused by the constant head-smashing associated with pro football. But instead of the gratitude he expected, the NFL, which had known about this and sat on it for decades, sends in the offense. As films about whistle-blowers go, this one lacks the satisfying punch of say, Erin Brockovich or The Insider. But the reason to see it is the precise, understated performance by Will Smith as Omalu, his best in years, backed up by Albert Brooks, Alec Baldwin and Gugu Mbatha-Raw. (123 min)