Recently widowed Matt Calder (Robert Mitchum) and his young son begin a new life in the breathtaking rugged Northwest wilderness where Matt is robbed and beaten by ruthless gambler Harry Weston (Rory Calhoun). When Weston's beautiful fiancée (Marilyn Monroe) then decides to nurse Calder back to health, the insanely jealous Weston risks all their lives by taking them on a ride down a treacherous river...