When Joe Fenderson dies from injuries sustained during a dockside mugging, Joaquin Shannon, a tuna boat skipper who is hated by Joe's father, assumes the blame to protect his brother-in-law-to-be, whom he believes is responsible. Sentenced to one to ten years in prison, Joaquin asks his girl friend, Jean Fenderson, Joe's sister, to wait for him, expecting to be paroled in a year. In prison, Joaquin does battle with Red Kincaid, a troublemaker and Joe's real killer. Red baits and frames Joaquin repeatedly, which causes Joaquin to fail his parole examination and lengthens his sentence. When Joaquin helps thwart an armed prison break led by Red, however, he is immediately released with three years of parole. Although Jean gladly reunites with him, Joaquin is shunned and dismissed by potential employers, forcing him to leave town and walk the streets. In a dingy bar, a hungry Joaquin meets Soapy, a fellow ex-convict, and unwittingly becomes entangled in a plan to smuggle Red, who has killed a guard while escaping from prison, out of the country. After Jean arrives at the boat to say goodbye to a still unsuspecting Joaquin, Red and Soapy, who was shot during the escape, show up and force Joaquin to navigate. A dying Soapy tells Jean that Red killed her brother. His enemy exposed, Joaquin fights to the death with Red, finally freeing himself from his troubled past.