Avsnitt 15

Professor Robinson is caught in a matter transfer emission ray, and subsequently ends up in another dimension where he is confronted by a version of himself and Don. However this realm is the opposite of his own dimension, the anti-matter world, where everything in reality is twisted. The evil John returns to the family and attempts to take over the Robinsons and take over John's life . Will he get away with it, or are Will and the Robot able to defeat him, and restore the world to it's natural order.