In Coaltown, Pennsylvania, miner Coke Mason hopes to better himself, buy a radio store, and marry Rose Warren. His gambler brother George thinks Coke can be more successful as a boxer, knowing that when he fights he's consumed with a murderous rage that makes him an "iron man." Seeing dollar signs in Rose's eyes, Coke reluctantly agrees, though he's fearful of the "killer instinct" that makes him a knockout success in the ring...and brings him the booing hatred of the fans. Will Coke throw off his personal demon before he kills someone?