Just in time for Christmas, Alan falls for Sandy, the teacher of his cooking class, and before long, she moves into the house, fattens the guys up with gourmet meals, drives Berta crazy with housekeeping tips, and generally turns all of their lives upside down with her unnatural pursuit of perfection. Charlie warns Alan that she's a "nester" and needs to be stopped before they reach a point of no return. Sandy turns out to be crazy for Santa.