U.S. Deputy Marshal Merlin Fanshaw is out of town on the day George Starkweather and his outlaw band hold up the Cattleman's Bank of Dry Creek. Upon his return, Fanshaw's boss, U.S. Marshal Chance Ridgeway, suggests the deputy volunteer to infiltrate the gang as an undercover agent. Fanshaw hesitates only a moment before agreeing. He and Starkweather have a dark history, and he's eager to bring his old nemesis to justice.