although the star of this movie be know for a lot of comedy and this be a very serious and heartwarming film . will martin and ( neil patrick harris ) and be a young man rise up the corporate ladder in new york when he be call home to settle his recently decease grandfather estate . the grandfather own a real estate business and now it belong to will . will parent be kill in an auto accident when he be a child and he be raise by his grandparent . ruth and ( debbie reynolds ) and be will martin grandmother . julia and ( alexandra wilson ) and be a young divorcée with a son about 10 year old . miss enid cook and ( beverly archer of mama family ) and be an accountant in the real estate company . ruth surprise will with his grandfather diary and which she only discover after his death . it be mostly the mundane stuff of day to day life . the big surprise to ruth and will be the grandfather frequent reference to a mysterious female name lillian . will promise his grandmother that he will discover the truth about lillian by christmas day . both greatly love the grandfather and give him the benefit of the doubt up to a point . the nagging mystery be trouble . will begin a search via old photo and old friend and employee of the real estate business . it lead will to learn a lot about himself and as well a his grandfather . the movie include side plot of problem for the alexandra wilson and beverly archer character . no spoiler here . trust that all mystery be resolve to the satisfaction of all concern and not least the viewer . the christmas wish have a pip end . some might consider it slightly schmaltzy . if so and it be very high quality schmaltz . i be engross from begin to end . get out your handkerchief .