Hired to steal the fabulous Queens Diamond, pint-sized jewel thief Calvin Simms and his dimwitted partner Percy stash the stone in Vanessa Chase's handbag when their getaway plans go uproariously awry. Discovering Vanessa's husband, Darryl, who's hopelessly obsessed with becoming a father, Calvin trades in his duds for diapers and poses as an abandoned baby. Suffering through a host of hysterical humiliations and outrageous family outings, Calvin desperately tries to retrieve the gem before his cover is blown, and Darryl and Vanessa really cut him down to size.