Department of Justice agent Richard Hood goes undercover in a small town near Kansas City after bills with serial numbers from a major robbery appear in the currency there. He boards at Aunt Ella's boardinghouse under the pseudonym Dick Grant and quietly goes to work around town to locate where the stolen money is being spent. At the boardinghouse, he befriends David Sherwood, who is cared for by his older sister Helen. Helen takes an instant disliking to Dick, in spite of his earnest attempts to befriend her. In the meantime, one of the robbers, Sam "Red" Hammond, who stays at the boardinghouse, is transporting food to the gangsters' hideout. Government agent Gabby Lambert arrives in the guise of a travelling salesman to assist Dick. With his help, they obtain fingerprints of the robbers, which they send to Washington, D.C. to be identified. Using binoculars found in Hammond's room, they determine the location of the hideout, and after hearing about a shootout at a nearby roadhouse, they go to the hideout. After Gabby goes in alone, the gangsters tie him up and shoot him. In the meantime, Dick intercepts a nurse, who was called to treat one of the injured gangsters, and takes her to the hideout. Suspicious of Dick's actions, Helen follows him. When the nurse does not cooperate, Dick handcuffs her to the car and goes into the hideout, where he discovers Gabby's dead body. After they make their escape, the gangsters kidnap David and Helen and head to a deserted factory. There, Dick and other federal agents capture or kill all of the gangsters, and Dick rescues David and returns him to Helen, who has new admiration for Dick.
