Judy sets out to find Maureen, while Will and Penny lead an expedition to the caves. Dr. Smith pursues a new escape plan.

While Dr. Smith moves ahead with his secret project, seismic activity wreaks havoc across the planet and leaves two teams facing impossible choices.

Flashbacks reveal clues to Dr. Smith’s past. The Robinsons contend with a new threat as the ship’s fuel supply starts dropping — fast.