The Robinsons' power source drops to critical levels, leaving them unable to recharge the Robot. Rather than endanger them, the Robot leaves the group. The crew looks for it and Will and Dr. Smith discover that the Robot has grown to be bigger than a house after exposure to strange gasses.moreless
The Robinsons' communications system is knocked out, and they discover that the culprit is a female warrior, who is planing on making their planet a colony for her people.
Dr. Smith discovers another android machine in the middle of a dangerous fissure. When he tries to order something, he is trapped inside the machine. Later when Will tries to get him out, he too is sucked in. Zumdish arrives on the planet in order to destroy the faulty, forgotten machine. Meanwhile, Will and Dr. Smith discover the magical Toymaker's world, as they are mistaken for toys.moreless
The Robinson family and Major West are imprisoned in their camp after being indicted to appear before a court for space crimes. As the trial begins, Dr. Smith's name begins to appear and it is not long before everyone realizes that all of the Robinson's "crimes" should be attributed to Smith, and he is indicted to appear before the court.moreless
Due to Dr. Smith's actions, the crew of the Jupiter II has had to land their ship on a alien planet which is run by cyborgs. The crew must rescue their crippled robot and then try to break free from the captors, even though the cyborgs promise them power and luxury for the rest of their lifes.moreless
After leaving their planet, Dr. Smith manages to plot a course back to Earth.
John Robinson becomes possessed by an alien creature who forces the family to prepare to return to the creature's home world, even if it requires that he sacrifice Will to keep his secret from the rest of the family.moreless
The Intergalactic Delivery Service comes to Priplanus. Once again Dr. Smith seeks transportation and has Will "test drive" the spaceship. Will returns much smarter than when he left. Smith, realizing the same increase of intellect could happen to him, boards the spaceship. His trip, however, ends in his rapid aging and subsequent impending death.moreless