In the near future, Earth is facing ecological collapse, and the Robinson family is chosen to travel to a distant planet, Alpha Prime, to establish a new colony. The family consists of Professor John Robinson, his wife Maureen, their children Judy, Penny, and Will, and Major Don West, the pilot. They embark on their journey aboard the spaceship Jupiter 2. Unbeknownst to the crew, Dr. Zachary Smith, a saboteur working for a terrorist organization, has stowed aboard and reprogrammed the ship's robot to destroy the mission. His plan backfires as he is trapped on the ship when it launches, and the sabotaged robot goes haywire, causing the Jupiter 2 to veer off course.

The spaceship, lost in uncharted space, faces numerous challenges as the Robinsons, along with Dr. Smith and Major West, encounter strange and dangerous phenomena. The family must work together to navigate through hostile environments, survive attacks from alien beings, and repair the damaged ship. Their journey is further complicated by the treacherous Dr. Smith, whose self-serving actions continue to jeopardize their mission. Trust and cooperation become crucial as they push forward in their struggle to find a way back to their intended path and ultimately toward their new home.