A ruthless crook, Walker (Lee Marvin), is betrayed by his partner, Mal Reese (John Vernon), who leaves him for dead on Alcatraz Island. Having survived, Walker returns years later to get revenge. He gets his first lead when a mysterious man (Keenan Wynn) tells him that Reese is now part of a vast criminal organization and dating Walker's wife's sister, Chris (Angie Dickinson). But after contacting Chris, Walker discovers that in truth she loathes Reese and is willing to help him get justice.