FBI agent Malcolm Turner is known best for being a brilliant, master of disguise. Malcolm's latest assignment sends him to small-town Georgia, where he's assigned to trap a brutal bank robber (and a recent prison escapee) who they suspect will be coming down to visit his ex-girlfriend Sherry and her son. Malcolm sets up a stakeout across from the home of a larger-than-life southern matriarch known as Big Momma, who's about to be visited by Sherry. It's a simple plan, but there's one big problem: Unbeknownst to Sherry, Big Momma has unexpectedly left town. So Malcolm, decides to impersonate the cantankerous Southern granny. Using a few tricks of disguise, he completely transforms himself into Big Momma, even taking on the corpulent septuagenarian's everyday routine-from cooking soul food to delivering babies to "testifying" at the local church. In the mean time, Malcolm starts falling for Sherry.