Molly Merchants

"It would be, dear, except for one thing. Prescott is not their accomplice. I am. (Kevin: You're.... You're the inside man?) I'm afraid so. (Kevin: "Mom"? He's your son?) I told you he was a handful. Go on.... (Kevin: Get off of me!)"

- Molly revealing herself as the inside man and her true nature

Molly Merchants is the hidden tertiary antagonist of Home Alone 4: Taking Back The House, though it is not revealed until near the end. She is the maid of a divorced Peter McCallister, the mother of Marv Merchants and of course his boss.

She is played by Barbara Babcock.

Biography
Molly along with her son Marv and daughter-in-law Vera planned to kidnap a Prince for ransom. She later began working undercover at the estate of Natalie as a waitress, as the Royal Family where to visit Natalie over the Christmas period.

Molly appears to be kind and supportive and seems to take a shine to Kevin (who was responsible for getting Marv imprisoned in the first two Home Alone movies). Although Kevin knows there is an inside man working for Marv and Vera, he initially believes it to be the shifty butler Prescott, allowing Molly to go on without suspicion.

On the day of the Royal family's arrival, Molly reveals herself to Kevin as the inside man, and has him locked away in the cellar with Prescott (who Kevin imprisoned in the cellar thinking he was the culprit). Molly, Marv and Vera await for the Royal Family's arrival, but end up finding themselves pursuing Kevin when he escapes the cellar and gets them involved in traps, with Molly later trapped inside an elevator.

After Kevin subdues both Marv and Vera, Molly escapes the elevator and attempts to attack Kevin but she is knocked out by Prescott. Molly is later arrested along with Marv and Vera and taken into custody.

Trivia

 * She could be considered the true main antagonist, as she is shown to be the boss of the operation and reminds Marv on an occasion that she is truly in charge.