FBI agent Malcolm Turner is tough, smart and a master of disguise. Malcolm’s latest assignment brings him to a small southern town, where he’s determined to trap a brutal bank robber (and recent prison escapee). Malcolm sets up a stakeout across from the home of a southern matriarch known as Big Momma, who’s about to be visited by the con’s former flame, Sherry, and her son. It’s a simple plan, but there’s one big problem: Big Momma has unexpectedly left town. So Malcolm, taking on his most challenging "role" ever, decides to impersonate the cantankerous Southern granny. In the process, Malcolm finds himself falling for Sherry, who might be hiding some stolen cash. Now, Malcolm/Big Momma must somehow find a way to get his man – and woman!