Following a tense effort to rescue John Robinson from deep space, the Jupiter 2 is drawn inside a massive alien spaceship. There, the family confronts a strange race of bubble creatures.
The Jupiter 2 lands on a planet Dr. Smith mistakenly believes is Earth. When Smith is lured out of the ship by cyborgs masquerading as earthlings, the Robot saves him - and the family - in the nick of time.
When Dr. Smith and Will discover a magic wish-granting machine, the family becomes intoxicated with greed. But the party ends when a strange alien creature reclaims the magic machine.
A friendly little dog survives the crash of a space capsule and leads Professor Robinson and Don West to Judy, just in time to save her from the claws of a giant hairy mutant.
Will comes up with an idea for a two-man ship that can travel to Earth. But when Dr. Smith hijacks the ship, a crash landing finds Will and Smith trapped in a jungle, pursued by a bush creature.
