Ex-insurance investigator Sykes reports to Marshal Morgan that he's pursuing a crook who stole $100,000 in a bungled payout that cost Sykes his job. Suspiciously, that crook is soon found dead along the roadside with the money missing.
Marshals Morgan and Ferguson are called in to investigate the murder of a postman and the theft of a sack of mail from his truck. The only clue to the crime is a broken bottle the killer drove over as he fled the scene of the crime. The lawmen find the shredded tire at a nearby gas station, but are curious why the operator is reluctant to assist in their investigation.
When a beautiful blonde who had approached Morgan about receiving a reward for providing information about tax evasion is found dead, the Marshal and his deputies investigate the owners of an import/export business who had been investigated previously for failure to pay their taxes.
A federal witness is murdered in New Mexico. When the suspects are spotted in Arizona, Marshal Morgan mobilizes his men to track the pair. One of the killers is captured in a garage, but the other, an oily ladies' man, hides out a remote farm and woos its pretty, but gullible, owner.
An elderly man strikes a woman who crossed the street in front of her, seriously injuring her. The driver insists that she was with a man, but she insists she was alone. Marshal Morgan is interested in the man who disappeared because he believes the other pedestrian was the woman's husband, who is wanted for murder and robbery in Chicago.
After Marshal Morgan captures a bank robber with $170,000 in marked bills, he decides to nab the unknown "high fence" who the crook was going to meet to launder the bills, as well. Deputy Tom Ferguson goes undercover, impersonating the criminal in hopes that he'll be contacted by the fence or his confederates to make a deal.
Morgan and Ferguson get a tip from a gas station attendant that he spotted a woman wanted for stealing bonds checking into a nearby motel. When the deputy arrives at the woman's room, he finds her strangled to death and the bonds gone.
An eccentric millionaire thwarts a safecracker's attempt to steal the hundreds of thousands of dollars he has hidden in his wall safe. But after Morgan and his men round up the gang, the safe is robbed anyway. Evidence points to an inside job - possibly a safecracker thought to be dead for almost ten years.