Teddy Duncan's middle-class family embarks on a plane flight from their Denver home to visit Mrs. Duncan's parents, the Blankenhoopers, in Palm Springs - all except daughter Teddy and mother Amy, for whom a cross country odyssey begins when a chance at free plane fare leads to a curtailed bus ride, a nightmarish experience in a Yugo, hitchhiking with a pair of alien abductees, and peddling through the desert on a tandem bike. All the while, the male Duncans survive a zany Christmas with Grandpa and Grandma Blankenhooper.