Undercover Agent Malcolm Turner is back and this time he's out to expose the suspected designer of a deadly computer "worm" that would allow outside forces access to sophistical and critical government intelligence files. But unfortunately, the only way the crafty agent can get next to the worm's creator, Tom Fuller, is to access the programmer's Orange County home as the new "nanny" to Fuller and his wife Leah's children: toddler Andrew and his two older sisters, Carrie and Molly. This means that Malcolm must once again rely on his sure-fire alter ego, the take-no-prisoners Hattie Mae Pierce, a.k.a. "Big Momma," to bring down the bad guys and prove that a woman's work is never done! But once undercover, the job proves another tough juggling act for Big Momma as "she" must manage the hectic lives of the three Fuller kids, keep up with their myriad of daily activities...