Plot

The film begins in an illegal underground dog-fighting arena in Korea, where an FBI agent, John Maxwell (Paul Giamatti), has been identified. He is ordered to be killed by his boss, but is rescued by his undercover colleague and master of disguise, Malcolm Turner (Martin Lawrence). Suddenly, FBI agents storm the place and arrest everyone inside. Meanwhile, in small-town Cartersville, Georgia, a criminal named Lester Vesco (Terrance Howard), who was serving a life sentence for murder and robbery, escapes from prison by killing the doctor and stealing his car. Malcolm and John are assigned to capture him, and were sent to Georgia to stake out the house of an elderly obese, Southern woman named Hattie Mae Pierce/Big Momma (Ella Mitchell), the grandmother of Lester’s ex-girlfriend, Sherry Pierce (Nia Long), who supposedly aided Lester in his original bank robbery by giving him the key to the vault. After Big Momma unexpectedly left town to help her friend for a couple of weeks, Malcolm and John sneak into her house to plant surveillance and tap the phones. Sherry calls the house and speaks on the answering machine. Malcolm disguises himself as Big Momma in an attempt to lure Sherry to Big Momma’s house and possibly obtain a confession. The plan works, and Malcolm and John work together on a Big Momma disguise costume before Sherry’s arrival the next day.

Sherry arrives at Big Momma’s house along with her 10-year-old son, Trent (Jascha Washington), but Malcolm’s inexperience with cooking and strange behavior prompt Sherry to believe that her grandmother might have gone senile. Worse, Malcolm also has to deal with Big Momma’s leacherous boyfriend, Benjamin “Ben” Rawley (Carl Wright), act as a mid-wife for her best friend Rita (Tichina Arnold) who has gone into labor, and attend self-defense classes under the local idiot, Terrance “Terry” Nolan (Anthony Anderson), whom Malcolm easily defeats and humiliates in front of all the other elderly women. After Malcolm almost damages the suit, during the night, he tries to sneak back to the house, where he and John are staying, but is caught by Sherry, and he poses as a “handyman” after just barely hiding the suit in a bush. Trent asks Malcolm what he is doing here. Malcolm tells Trent that Big Momma has been talking all about him. Trent says that she has not, and Malcolm says that she has. Trent only knows a little bit of karate. Malcolm tells Trent to show him a bit of his moves, and does a kung-fu move. John wakes up, and sees Malcolm and Trent doing karate through his window. Malcolm and John repair the suit, and when Malcolm leaves for town with Sherry as Big Momma, John searches the house for any trace of the money Lester had stolen from the bank (which was never recovered), but to no avail. Malcolm also bonds with Trent as Big Momma when he defends him against a group of elder boys, who had told him to leave the public basketball court, so that they can play. Malcolm and Trent beat the boys at basketball, amazing both Trent and Nolan, who was watching from afar.

Malcolm, as himself, also begins to bond with both Sherry and Trent, accompanying them on a fishing trip. After Malcolm returns to John that night, Nolan bursts in and attempts to arrest them for “dismembering” Big Momma, but Malcolm emerges in the body suit, and they reluctantly recruit Nolan to help them out, promising him that they will recommend him for a place on the FBI if he succeeds. Big Momma’s birthday arrives, and Malcolm, Sherry, and Trent celebrate by going to church, and then organizing a surprise party at her house. However, during the party, the real Big Momma returned early after helping her friend, and John attempts to stall her. Meanwhile, Malcolm, still in disguise, accidentally stumbles across the stolen money hidden in Trent’s footlocker. Sherry sees this, and tells Malcolm the real story: Lester had merely been playing her for a fool the whole time. He wooed her, stole her keys and got into the vault, during the robbery, and Sherry didn’t tell anyone out of fear of losing her job. Malcolm goes off to call his name to help them out. Meanwhile, John quietly tells Nolan in the bathroom that the real Big Momma has returned early, and Nolan accidentally locks Malcolm out of the house, believing that he is the real Big Momma. Meanwhile, Lester arrives in Big Momma’s house, having tracked Sherry, Trent and the money, and tries to take them out of the country with him, but after Sherry says goodbye to the real and delighted Big Momma, Nolan spots Lester’s gun and tries to arrest him, but accidentally unloads his gun. However, before Lester can kill Nolan with his gun, Malcolm bursts through the window and fights Lester, himself. In the ensuing fight, Lester shot John in his shoulder and rips Malcolm’s mask, revealing him. Nonetheless, Malcolm subdues Lester and knocks him out from the window. Sherry and Trent were heartbroken to realize Malcolm was an FBI agent the whole time, and they refuse to speak to him, even as Lester is arrested and John is taken to the hospital for his arm surgery.

In the film’s climax, Malcolm goes to the church on Sunday morning to make a testimony, where Sherry, Trent, and Big Momma are there for a mass. Malcolm delivers his promised speech to Sherry and Trent and admits that he genuinely loves them. Big Momma forgives Malcolm with a big, strong hug, and the crowd cheers, as Malcolm and Sherry kiss each other. Malcolm invites Trent over for a group hug and everyone celebrates as Big Momma sings “Oh Happy Day” during the closing credits.

Cast

• Martin Lawrence as FBI Agent Malcolm Turner
• Nia Long as Sherry Pierce
• Paul Giamatti as John Maxwell
• Jascha Washington as Trent Pierce
• Terrence Howard as Lester Vesco
• Anthony Anderson as Terrence “Terry” Nolan
• Ella Mitchell as Hattie Mae Pierce/Big Momma
• Phyllis Applegate as Sadie
• Starletta DuPois as Miss Patterson
• Octavia Spencer as Twila
• Tichina Arnold as Ritha Nolan
• Nicole Prescott as Lena
• Cedric the Entertainer as The Reverend
• Carl Wright as Benjamin “Ben” Rawley
• Jimmy Westermeier as “The Mailman”