Andy has a sweet Catholic mother, a sour Catholic father and an intellectually disabled younger brother named Mickey. When he brings his Jewish atheist fiance to meet the folks on Christmas Eve, his worst fears about family blow-ups are realized. But when Mickey, whose entire vocabulary has been limited to "oh boy" and "wow," suddenly spouts the word "Greetings!" the entire family's belief system is turned upside down. For it seems an ancient, wise and witty spirit who is set upon healing the family's wounds has borrowed Mickey's body!