Ray “Boom Boom” Mancini went from working class Youngstown Ohio kid to boxing superstar, but when he accidentally kills opponent Duk Koo Kim during a 1982 bout live on CBS SPORTS, he becomes racked by guilt and regret. Thirty years later, when Kim’s grown son, Jiwan, decides he would like to meet the man responsible for his father’s death, both men have the opportunity to find some closure and bring decades of pain to an end. A tale of fathers and sons, Miller’s documentary is more than just a slick, well-made biopic of a fascinating sportsman: it’s an exploration of the consuming nature of grief and the power of forgiveness.