Professor John Robinson, his wife Maureen, their daughters Judy and Penny, and son Will are selected to be the first family to colonize outer space. Piloted by Major Don West, Jupiter 2 takes off to Alpha Prime, the only other habitable planet in the galaxy. En route, their spacecraft is sabotaged by arch-villain Dr. Zachary Smith, who is intent on foiling their plan. When Jupiter 2 strays dangerously off course, the Robinson family must band together and use their unique skills to complete their mission or face certain death while they remain "lost in space.