Fleeing plummeting temperatures plunging, the Robinsons have abandoned the crashed Jupiter 2 spacecraft and head south in the chariot in a desperate bid for survival. Dr. Smith refuses to accompany the family and Major West, and remains behind with the Robot on the ship. Arriving back at the Jupiter 2, the Robinsons and Smith find they had both reached the same explanation for the planet's extreme temperature swings, but with the worst over, they are able to resume their work in establishing themselves on their new home.