An insurance agent's greedy wife leads him to a life of crime.

After insurance investigator Joe Peters wraps up a difficult case in Cincinnati, he prepares to fly home to Los Angeles. Once on board the plane, he realizes that fellow passenger Diane Morley is posing as his wife in order to fly for half-price, but does not report her. When a storm forces the plane to land in Kansas, Joe and Diane end up sharing a hotel room because of their marital "status." Joe expresses his disapproval of Diane's gold-digging ways, but is nonetheless attracted to her. The seductive Diane rejects Joe's kiss, explaining that he is not rich enough to woo her, and upon arriving in Los Angeles, says a curt goodbye. Soon after, Joe and his partner, Harry Miller, are sent to investigate a fur company robbery, which they suspect was engineered by wealthy racketeer Kendall Webb. Just before Christmas, while spying on Webb at a nightclub, Joe sees a fur-coated Diane by Webb's side. Although Diane claims to have earned the coat modeling, Joe is skeptical and refuses to return her kiss. Joe and Harry's suspicions increase when they see Diane showing off another fur coat in Webb's apartment. Joe still desires Diane, however, and sneaks into her apartment to decorate a Christmas tree for her. Although Diane admits to Joe that she has feelings for him, she maintains that she will never be happy on his paltry detective's salary. Later, Joe reads a memo about an upcoming million-dollar cash shipment that his company is insuring and gets an idea. Aware that Webb controls a vast criminal network, Joe offers him inside information about the shipment in exchange for one-third of the stolen money. Webb agrees to the plan, but on Christmas Eve, after Webb abandons her to spend the holiday with his family, Diane tells Joe that she wants to marry him, rich or poor. Stunned but happy, Joe tries to back out of the heist, but Webb convinces him that, sooner or later, he will need money to keep Diane. After Joe and Webb work out the details of the robbery, which is to be committed on a train by five of Webb's men, Joe and an unsuspecting Diane marry and head for the mountains of northern California, where Joe and Harry co-own a cabin. A week later, on the day of the heist, Joe starts to act nervous and Diane demands to know why. Joe admits all to Diane, who finally sees how her past greed now threatens their happiness. In their cabin, the couple listen to a radio report about the heist and learn that all the robbers escaped with the cash. The next day, Joe is summoned to investigate the theft, but before he goes, he picks up a fire extinguisher in which Webb has sent his share of the loot. In Los Angeles, Harry and Ray Egan, another investigator, inform Joe that, because the robbers knew exactly where to find the money, they suspect an "inside man" was involved. Noting that any one of them could be guilty, Egan runs down Joe's recent activities, including the receipt of the fire extinguisher, and clears him. After the detectives conclude that the robbers escaped with the help of an amphibious plane, they track down the plane and question the pilot, Partos. Partos eventually identifies one robber, De Vita, from police mug shots, and De Vita is hauled in for questioning. Concerned, Joe calls Webb, but Webb informs him that De Vita will never talk, especially if he is roughed up. To assure De Vita's silence, Joe starts to beat him during his interrogation. Joe's uncharacteristic outburst arouses Harry's suspicions, and he shows up later at Joe and Diane's apartment and speculates that Webb, a known associate of De Vita, is probably behind the heist. Convinced that Harry will soon unravel the mystery, Joe telephones Webb and lies that De Vita "sang" and they must now meet. Joe directs Webb to a remote spot, where he knocks him out, shoves him in his car and causes the car to crash and burn. Posing as Webb, Joe then sends a wire to Webb's wife, informing her that she will soon be receiving a parcel, which she is to place in a safe deposit box. Later, after Webb's wife is caught depositing some of the heist money, and Harry and Egan identify some half-burnt cash that was found in Webb's car as part of the loot, they realize that a third of the money is still unaccounted for. Harry then accuses Joe of being the inside man, noting that he, Harry, had recently bought an extinguisher for the cabin and knows that it could easily hold bundles of cash. Joe admits his guilt but flees from Harry before he can arrest him. Joe picks up Diane, and they head south for the border, but are soon trapped in a police dragnet. To save Diane, Joe forces her out of his car along the Los Angeles River bed, then is shot by the police. After Joe dies in Diane's arms, Diane stumbles off to face an uncertain future.