AllMovie

The Robinsons come across some gigantic "cyclamen" planets, capable of duplicating whatever is fed to them. As a means of increasing the space travellers' fuel supply--and to prevent the Robinsons from punishing him for his past misdeeds--Dr. Smith (Jonathan Harris) feeds the remaining fuel to the plants. Unfortunately, the plants also yield an evil doppelganger of Judy Robinson (Marta Kristen), who threatens to wreak havoc upon everyone. Only Dr. Smith knows where the "real" Judy is--and he demands a hefty price to reveal this information.