The Jupiter 2 is travelling through space. On board, the Robinson party is celebrating the Robot's birthday. Dr. Smith decides to take the Space Pod down to a planet that they are passing to get him some flowers as a birthday gift. The planet does not have any members of the animal kingdom living on it. It is completely inhabited by plants. One of these plants, a giant carrot, captures Dr. Smith. He then proceeds to capture most of the remaining Robinson party when they land with the Jupiter 2 to rescue Dr. Smith.