A shoplifter, Faye Burton, is being watched by Herb Klaxon, a security guard at a Los Angeles department store, and by Jeff Andrews, a shopper there. Jeff tries to warn her, but Faye is nevertheless caught and placed under arrest. Faye signs a confession and is set free, warned that if she tries this again, she will go to jail.

Faye returns to her job as a librarian, but a gang of thieves run by Ina Perdue, a pawnbroker, recruits Faye by claiming they can get her confession back, thereby clearing her record. Faye is shown by Ina and her henchman Pepe how to steal like a professional thief, and is then given a San Diego robbery assignment as a test. She is followed by Jeff, who is actually an undercover law officer, working to bust the shoplifting ring.

Pepe attempts to sexually assault Faye, who becomes so despondent, she tries to commit suicide. Jeff rescues her and reveals his true identity. They arrange to work together, but Jeff's cover is blown and Faye is kidnapped. Ina and Pepe take her to Mexico to continue their crime spree, but Jeff and his men arrive in time to apprehend the crooks. Jeff also realizes he has fallen in love with Faye.

• Scott Brady as Jeff Andrews
• Mona Freeman as Faye Burton
• Andrea King as Ina Perdue
• Tony Curtis as Pepe (as Anthony Curtis)
• Charles Drake as Herb Klaxon
• Gregg Martell as The Champ
• Larry Keating as Harry Dunson
• Robert Gist as Barkie Neff
• Michael Raffetto as Sheriff Bascom

• I Was a Shoplifter at IMDb  
• I Was a Shoplifter at the American Film Institute Catalog
• I Was a Shoplifter at the TCM Movie Database