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 Penny and Dr Smith are using the Ouija Board, Dr Smith's fingers change position when the camera zooms in on them. See more
Warning! Warning! Unidentified object caught in trap. Warning! Unidentified object caught in trap. Unidentified object exerting full power to get out of trap. Warning! Warning! Unidentified object exerting full power to get out of trap. Warning! Warning! Warning! Warning! Warning!
Dr. Zachary Smith
Now you've done it! You've given the powers of darkness an open invitation to destroy us all!