Stan (Charlie Hunnam) and Lion (Jack O'Connell) are two brothers struggling to stay relevant in the underground world of bare-knuckle boxing. When Stan fails to pay back a dangerous crime boss (Jonathan Majors), they're forced to deliver an unexpected traveler as they journey across the country for a high-stakes fighting tournament. While Stan trains Lion for the fight of his life, a series of events threaten to tear the brothers apart but their love for one another and belief in a better life keep them going in this gripping drama that proves family pulls no punches.