When Uncle Al is kidnapped by Dr. Kron-Tox and sent to prehistoric times, Andrew, his cousin Judy, and Thudd the robot try to use Uncle Al's latest invention, the Time-A-Tron, to rescue him, and learn first-hand about the origins of the universe.

When Beeper accidentally releases the escape hatch to the Time-a-Tron, the time travelers must protect themselves from the world's most fearsome creature, Tyrannosaurus rex.

Still trying to stop the evil Dr. Kron-Tox, Andrew, his cousin Judy, Thudd the robot, and Beeper find Uncle Al in the Ice Age, where they encounter prehistoric animals, birds, and people.