After Dr Smith is turned away from camp yet again, he awakes from a nap to find he has been tied up by little mechanical men. The Robinson's camp is invaded the mechanical men of INDUSTRO, who claim that they want a leader..their leader. The Robinson's learn that the Robot is what they want, and that if he is not surrendered the mechanical men will attack. When the Robot surrenders, the mechanical men realise he is not the ""evil"" leader they wanted and they subsequently switch his personality with Dr Smith. An attack occurs when Dr Smith returns to camp wth the voice and personality of the Robot, which Don finds hilarious, and uses to full advantage. An attack ensues and the mechanical men are defeated and turn Dr Smith and the Robot back.