FBI agent Malcolm Turner is tough, smart and a master of disguise. There's nothing he can't handle. So Malcolm, taking on his most challenging "role" ever, decides to impersonate the cantankerous Southern granny Big Momma. 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.