Convinced of his friend's innocence, a friend disguised as a minister switches places with a suspect accused of mail robbery and murder and allows him to escape. While Marshal Morgan's men search for the escapee, another man who was implicated in the crime is found recently shot to death along with mail sack containing part of the loot.
Morgan and Ferguson search for a missing deputy who had been sent to arrest a fugitive believed to be living in a tiny mountain community, but find the local constable uncooperative and the townspeople hostile.
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.
When a truck carrying top secret missile parts disappears en route to a military base, Marshal Morgan and Deputy Ferguson join the search. During their investigation, they encounter an eccentric Englishman, an old country store operator who doubles as town constable and justice of the peace, a pair of wary café operators and an all-night gas station operator with something to hide.
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.