Synopsis by Hal Erickson
Thrown wildly off course, the Jupiter 2 reaches the gravitation field of an uncharted planet. Exploring this strange new world in search of life signs, John Robinson (Guy Williams) vanishes shortly after his "parajet" runs out of fuel. Under the guidance of John's wife Maureen (June Lockhart), the rest of the space travelers disembark on the planet's surface and begin a search mission in their all-purpose "space chariot." Meanwhile, evil Dr. Smith (Jonathan Harris) persists in his efforts to sabotage the mission with the aid of his killer robot. Much of the footage in this episode is lifted from the original Lost in Space pilot film, in which neither Smith nor the robot appeared.