A rigid police detective accidentally uncovers his wife's illegal past.

Outside New York's busy 21st Precinct, police detective Jim McLeod spends a romantic moment with his devoted wife Mary, then escorts embezzler Arthur Kindred into the station. While booking Arthur, Jim tries to telephone Joy Carmichael, Arthur's childhood sweetheart, and informs her sister Susan about the young man's arrest. Jim then encounters Endicott Sims, a lawyer representing Karl Schneider, a New Jersey baby broker wanted on murder charges. Sims has just informed Jim's lieutenant, Monahan, that Schneider wants to turn himself in without incident and warns Jim not to touch his client. The volatile Jim openly expresses his hatred of Schneider, accusing him of murdering young girls. Jim's hard-drinking partner, Lou Brody, questions Arthur alone, and seeing his own dead son in the troubled war veteran, is sympathetic. Just then, two burglary suspects, Charley Gennini and Lewis Abbott, are brought in. With Lou's help, Jim interrogates both men and turns the slow-witted Lewis against Charley. After Jim promises to "go easy" on him if he cooperates, Lewis admits that the stolen loot is at Charley's place. To Arthur's chagrin, Susan then shows up at the station, worried and anxious. Arthur, who embezzled $480 in order to impress Joy, a successful model, tries to discourage Susan and sends her home. When Schneider arrives with Sims, Jim informs him that his baby broker "partner," Miss Hatch, has implicated him and will pick him out of a lineup. To Jim's disgust, Schneider has bribed Miss Hatch with a fur coat, and she refuses to identify him. Jim explodes and admits to reporter Joe Feinson that his hatred for his father, who drove his mother to an insane asylum with his unrelenting cruelty, has made him into a crusader against evil. Jim then decides to take Schneider to Bellevue Hospital, where a young victim of Schneider's "butchery" is being treated. On the way there, however, Jim learns that the woman has died, and without her identification, Jim has no case against Schneider. As they head back to the station, Jim threatens Schneider, who smugly declares that he has "friends in high places." Enraged, Jim slaps and punches Schneider until he collapses. Before leaving in an ambulance, Schneider tells Monahan that Jim is after him because of a man named Tami Giacoppetti. Although Jim denies knowing Giacoppetti, a racketeer, Monahan discreetly orders that both Giacoppetti and Mary be brought in. Meanwhile, Arthur's boss, Albert R. Pritchett, shows up to file charges against Arthur. While Pritchett questions Arthur about his motives, Susan returns and gives Pritchett $120 she scraped together. Calling Arthur a thief, Jim tries to dissuade Susan from helping him, but she pleads with Pritchett, swearing that the embezzled funds will be repaid. After Monahan sends Jim off on an errand, Lou steps in and all but convinces Pritchett to drop the charges. Mary then arrives and talks privately with Monahan. Monahan tells Mary, who has been trying to have a baby with Jim, about Jim's assault on Schneider and asks her about her past. At first, Mary denies knowing Giacoppetti and Schneider, but when Giacoppetti walks in and greets her, she runs out, crying. Unaware of what has just transpired, Jim returns and yells at Lou for interfering with Arthur, then orders Pritchett to press charges. Jim also rails against Charley, whose long rap sheet gives lie to his claims of innocence. Meanwhile, in his office, Monahan persuades Giacoppetti to reveal that years before, Mary became pregnant by him but, as he was married, decided to give the infant up. The baby was born dead at Schneider's "baby farm," and Giacoppetti never saw Mary again. Moments later, in front of Jim, a distraught Mary insists to Monahan that Jim knows nothing about her past. Confused, Monahan brings Mary and Jim into his office, where Mary confesses all to her husband. Once alone with Jim, Mary begs his forgiveness, but he calls her a tramp and asks if her infertility is the result of Schneider's handiwork. Stunned by Jim's harshness, Mary leaves in tears. Later, on the precinct rooftop, Lou approaches Jim and beseeches him to give Arthur a second chance, but Jim refuses. Joe then joins them and urges Jim to make amends with Mary while he still can. Jim finds Mary, who has come to the station to say goodbye, and pleads with her to stay. Mary relents, but after Sims makes a snide comment about Mary's love life, Jim admits to Mary that he cannot wash away the "dirty pictures" she has planted in his mind. Calling him cruel and vengeful like his father, Mary leaves Jim for good. Though numb with the knowledge that he has become the thing he most hates, Jim returns to booking Arthur. Just then, Charley, taking advantage of the station chaos, grabs a gun from a detective's holster and threatens to fire it. Fearlessly Jim advances on Charley, who shoots him repeatedly. After Charley is subdued, Jim asks Lou to release Arthur, then dies from his wounds. Lou frees Arthur, who walks out of the station with the faithful Susan by his side.