Returning to his home town after the death of the grandfather who raised him, slick and cynical Wall Street trader Will Martin (Neil Patrick Harris) feels decidedly out of place, and not at all in tune with the Christmas preparations being made by the local citizenry. But Will isn't really taking a sentimental journey at all: He's merely in town to modernize and streamline his family's real-estate company. While going through his grandfather's effects, Will and his grandmother (Debbie Reynolds) come across the old man's diary--which reveals a lengthy relationship with a woman named Lillian. Determined to locate this mystery mistress (if indeed that's who Lillian is), Will learns a few vital lessons about love, forgiveness, and recapturing the Yuletide spirit that has so long eluded him.