Seven months after arriving in a new star system the Robinsons have built something of a new life for themselves on the surface of a new world. But hope for a better life -- and new dangers -- push them into a risky plan to cross an ocean and re-power the ship.
With the Jupiter hanging on the edge of a waterfall the crew rallies to catch the coming lightning storm. But new crisis strike first when Don is injured, and Maureen and Penny are stranded at the bottom of the alien trench.
The Robinsons expect a homecoming when the ship docks with the Resolute, only to find the ship abandoned. While Dr. Smith works to cover her tracks, the kids discover evidence that the Robot may be nearby.
Penny, John, and Don travel to the surface of a temporary colony world to help the colonists prepare for their return to the Resolute. Will goes in search of his Robot, and ends up having an encounter with another of its species.
After her father is critically wounded inside the well, Judy risks her life to get back to the dig site to treat him. Elsewhere, Penny enlists the help of a friend to get proof of Dr. Smith's latest crime.
Penny and Vijay find themselves trapped with their teacher and Dr. Smith after the Resolute is infected by the alien contaminant. Maureen, Will, and Adler land on the planet's surface to search for the Robot.
Adler begins to see how unique Will's Robot is as they make their way across the wilderness to the pick-up point. Back on the Resolute John enlists Dr. Smith's help to learn more about a looming new threat.
While the Robot attempts to leave the ship with his injured friend, Maureen and John find themselves separated from the Resolute when Hastings takes action to strand them.
As the colonists evacuate, John and Adler attempt to save Scarecrow by taking him to the planet's surface. But when a horde of robots attack the Resolute directly, the Robinsons are faced with an impossible decision to save the future.
