The Robinson party comes under a new threat created by Dr. Smith when he ditches an explosive in a bog full of ionized gas. The result is an invisible monster that abhors sunlight. Dr. Smith believes it's the ghost of his Uncle Thaddeus, returned from the spirit world to vent his displeasure at non-believers. Smith's efforts to placate this "spirit" puts at least one of the Robinson children in particular peril. Written by
Did You Know?
To trap the invisible creature, John and Don use the cage left behind by the Keeper. See more
When the creature is in its invisibility state, its footprints are shown to be three-toed. However, when the creature materializes, there are more than three toes and each toe has a large claw turned and pointed downward. See more
You know, when I was a little girl, we found a Ouija board up in my grandmother's attic. Trouble was, nobody know how... what to do with it, even my grandmother. I'm afraid it's quite obsolete in the world of computers.
Maj. Don West
Uh, so's Dr. Smith, but then, again, I'm not sure what world he really belongs in.