A short-statured, but adult-aged career criminal, after being released from prison, plans to retire by stealing a valuable diamond. During the heist, his attempt to escape the scene goes awry, leading him to cleverly hide the diamond in a woman's purse. Desperate to retrieve the diamond without attracting the attention of the police, he hatches a convoluted plan: he decides to pose as an abandoned baby left on the doorstep of the woman's home. The woman, along with her husband, unsuspectingly takes in what they believe is a foundling, opening their home and lives to someone they think is a child in need.

As the couple becomes increasingly attached to their new "baby," the criminal works to retrieve the hidden diamond without blowing his cover. However, his attempts are continuously thwarted by unexpected domestic bliss and the normal challenges of living under the guise of an infant. This family dynamic opens a comical pandora's box of nurturing, bonding, and a series of comedic events that strew the path of the criminal's originally simple plan to recover the stolen gem. His interactions with the family and surrounding community unwittingly draw him into a more complicated and less criminal world than he's used to, testing his morals and his ultimate desire to lead a life of crime.