In Berlin in 1946, Corp. Harry Craven delivers counterfeit bills to a driver who then shoots and kills him. Soon afterward, U.S. Treasury agent Maury Saxon questions Staff Sgt. Johnny Salvo, who roomed with Craven first in jail and then in the Army. Maury offers Johnny, whose jail term was deferred when he joined the Army, a full pardon in exchange for his help tracking down Craven’s partners. Johnny agrees, but when he discovers that he is to work under his father, agent Alec Conrad, he refuses. Alec enters the room and pleads with Johnny to accept, hoping the assignment will heal the rift between them that began when Alec tried to reform Johnny, a petty hoodlum, by turning him in to the police. Although he remains bitter toward his father, Johnny accepts the job in order to receive a pardon. Days later in Los Angeles, Maury cautions Alec not to let his desire to reconcile with Johnny detract from the case, after which agent Phil Schwartz escorts Johnny to a briefing. There, Alec describes to the assembled agents the counterfeiting ring created by Emile Reinhardt, who disappeared in 1939 but whose near-perfect bills have now reappeared. Knowing only that the bills’s paper and ink come from a Seattle firm, Alec instructs his men to investigate which companies have ordered the paper recently, and sends Johnny, working undercover, to question Craven’s wife Maria. At Maria’s house, family friend Don Kastner receives Johnny rudely, but Johnny earns Maria’s trust by proving his intimate knowledge of Craven. Later that night, not realizing that Kastner has followed them, Maria invites Johnny for a drive and they find themselves romantically attracted. Soon after, immigrants Mr. and Mrs. Pulenski are caught with counterfeit bills and Alec must inform them that the dollars, for which they traded their life savings, are useless. Johnny then enters Alec’s office to report that Maria knows nothing, arousing Alec’s suspicion that Johnny has becomes attracted to Maria. Alec then attempts to discuss the past with his son, but once again Johnny turns away. Maury interrupts them with information about the Pulenskis’ neighborhood, the name of which Johnny recognizes from Craven’s file. The next night, Maria invites Johnny to a restaurant owned by Mama Gomez, whose new husband Milo clandestinely calls Kastner to inform him of Maria’s presence. Maria and Johnny share a dance that ends in a kiss, but as soon as he returns home, Kastner and two thugs beat him up. After they leave, Alec calls and, hearing that Johnny is in distress, rushes over. Although Johnny instructs Alec to stay out of the affair, he secretly appreciates his father’s interest. Soon after, the agents narrow their search for paper and ink buyers to importer Philip Bormann, for whom both Kastner and Maria work. A bruised Johnny goes to Bormann’s office, where he punches Kastner in front of Maria and Bormann. He returns to the Treasury building, but when Phil passes Johnny and notices Kastner tailing him, he surreptitiously warns Johnny, who avoids the Treasury suite and instead pretends to be visiting the probation office. Phil then tails Kastner and informs Alec about him, and in response, Alec demands that Johnny quit the case, fearing that his attraction to Maria will lead him into danger. Johnny pleads with his father to allow him to continue, but Alec will not take the risk, so Johnny vows to learn the truth about Maria on his own. As Bormann and Kastner discuss how to deter Johnny, Alec’s team learns that Bormann sends back supposedly inferior packages over the border each month, and deduce that these packages contain the contraband bills. When Kastner drives Maria home from work that night, he threatens to kill her if she does not marry him, and she later sneaks over to Johnny’s hotel for protection. Johnny confesses his love for her and asks her to accompany him to his upcoming military assignment, and Maria agrees. Days later, Phil tracks Bormann’s paper delivery as the packages of paper are dropped off at Milo’s restaurant and transferred to a truck, which drives away. When Phil tries to stop Milo, Milo knocks him out and flees, but is killed by another agent. Alec’s team arrives to clean out the restaurant’s back room, which they find filled with counterfeiting equipment. Although they detain Bormann, they cannot hold him without evidence. The next day, however, the agents seize Bormann’s latest returned shipment and, after tearing apart the bolts of paper, discover the bills inside and arrest him. Meanwhile, Kastner goes to Maria's and, discovering that she and Johnny have left for the train station, follows them there in a jealous rage. He arrives at the same time as Alec, who has come to beg Johnny for forgiveness. When Kastner shoots at Johnny, Alec steps in front of the bullet. Johnny pursues Kastner through the train station and finally overcomes him, allowing the police to arrest him. As Alec is brought to the hospital, wounded but alive, Johnny agrees with Maria that he has a wonderful father.