Director Rebecca Carpenter's father, Lewis Carpenter, was a running back for Vince Lombardi's NFL Champion Green Bay Packers. When he dies, her family receives a surprise call from Boston University's brain bank requesting his brain - with shocking results. Lew becomes the 18th NFL player diagnosed postmortem with Chronic Traumatic Encephalopathy (CTE), a degenerative neurocognitive disorder that can cause episodes of rage, social withdrawal, and other unusual behaviors. Carpenter finds herself at ground zero of an unfolding public health controversy and embarks on a three-year odyssey across America to explore the far-reaching implications of this "new" disease in football players. Carpenter approaches her subjects with refreshing humor, manic curiosity, and a huge heart as her father's former teammates and adversaries, scientists, historians, and other families affected by CTE offer their insights and support. Through quirky and poignant visits with family friends, former NFL players, and headline-stealing scientists such as Dr. Bennet Omalu, Rebecca pursues a mystery decades in the making. From NFL Hall of Famers like Mike Ditka and James Lofton, to neuropathologist Dr. Ann McKee, she begins to understand the depression, obsessiveness, forgetfulness, and unpredictable temper that often complicated her relationship with her dad are common side effects of repeat blunt force trauma to the brain.