Mike Jason, [Dennis O'Keefe], a radio personality, tries to boost ratings for his murder-mystery show by offering a $10,000 reward to anyone who can locate the legendary safecracker Jimmy Valentine, rumored to have retired. The promise stirs up the airwaves and draws a curious mix of listeners and locals into a town-wide hunt.
Mousey Scarlatti, [George E. Stone], a rough-edged, eager figure, becomes fired up about the chance to claim the prize and prove himself. Valentine is said to have wandered into Fernville, a quaint, picturesque town in Illinois, leaving Jason and his team both intrigued and wary of the quiet community they’re about to shake up.
Jason, along with his on-air partner Cleo Arden, [Gloria Dickson], and accompanied by Mousey, travels to Fernville to start the search. Their arrival unsettles the town, and the trio’s presence unsettles old, sleeping secrets that many would rather keep hidden. The hunt begins with a trip to the town’s local newspaper, where Jason hopes to unearth forgotten files that might pinpoint Valentine’s whereabouts.
There, Jason meets Bonnie Forbes, [Ruth Terry], the editor’s daughter who has a growing interest in the investigation and offers to lend a hand. She leads the group to her father, Tom Forbes, [Roman Bohnen], the editor who isn’t quick to jump on the pursuit. Bonnie’s budding romance with Jason gives the mission a personal edge, and she pushes the team to keep digging. She also guides them to Tom’s gardener, Pinky Dolan, [Harry Shannon], a man who has heard stories about Valentine from years past.
Pinky initially claims to know nothing helpful, but as Jason and Mousey press deeper, they glimpse Pinky rummaging through Tom’s office and uncover a photo of Pinky from years ago, a clue that his hair color once matched Valentine’s old sidekick. The discovery links Pinky to Valentine in a way that complicates the town’s tidy narratives and stirs old resentments.
As the plot thickens, Mousey reveals a darker motive: he is the son of a notorious mobster who was framed by Valentine, and he acts out of revenge. In a violent moment, Mousey kills Pinky, an act that sends Jason’s suspicions spiraling. He suspects Valentine of being the killer, and his suspicions push the town into a frenzy as he begins collecting fingerprints from prominent residents to expose the truth.
The prints are stored in a safe at the sheriff’s office, and Jason devises a plan to ambush Valentine when he attempts to crack the safe and seize the prints. Just as the plan unfolds, Jason confronts Tom, who turns out to be Jimmy Valentine, the burglar himself, breaking the safe in a dramatic reveal. To spare the rest of the town from ruin, Tom proposes to hand over his own prints in exchange for amnesty for everyone else involved.
In the ensuing chaos, Mousey intercepts, trying to exact his revenge on Tom/Jimmy, and in a shocking twist, Mousey ends up killing himself. Jason learns that Pinky was, in fact, Jimmy Valentine in disguise, a revelation that clears Tom and protects his daughter from ruin. With the truth laid bare and the danger behind them, Jason decides to remain in Fernville, choosing to stay with Bonnie as they begin a new chapter in the small town they helped shake awake.
