The alien robots attack the Resolute, and the crew tries to evacuate before the invaders destroy them.

The Robinson children realize where the Robot is trying to take Scarecrow and help it escape the Resolute, and gain an unexpected ally Hastings strands John and Maureen in the gas giant.

Maureen takes control of the Resolute from Kamal to rescue the stranded colonists. John and Judy have a meeting of minds with Hastings, Don tries to help the OGS crew, and Will and Penny discover the Robot has another priority than helping them.

Kamal and Hastings receive an unidentified audio signal and John sets out to discover what it is. The Robot makes a friend and then loses it, and Ben has a change of heart.

Penny tries to find a way for her and the others to escape the spreading contaminant. On the planet, Maureen, Will, and Ben find the Robot... or do they?

Judy runs against time to save John after the drill shaft collapses. Penny convinces Vijay to help her gather evidence against Smith, and Maureen and Will travel to the planet with Ben to investigate Will's connection to the Robot.

The Robinsons are reunited with the Resolute survivors. Smith takes advantage of a bookmark, Will makes a new friend, John checks out a drill shaft, and Judy discovers that her medical experience doesn't count for as much as she hoped.

The Robinsons find the Resolute on their side of the rift and abandoned, and are soon evading one of the alien robots. Meanwhile, Smith takes steps to erase evidence of her old life and remembers the past.

Penny and Maureen are swept into the trench, and the Robinsons try to figure out a way to rescue them before the lightning storm hits. Meanwhile, Smith reads Penny's book and learns about Don's past.

The Robinsons and Don are forced to convert the stranded Jupiter 2 into a sailing ship when the hull springs a leak, letting in poisonous atmosphere. Smith sets out to prove her usefulness, and Will misses the Robot.