Penny Appleby (Susan Strasberg) is a paralyzed young woman confined to a wheelchair. For the first time in ten years, she has returned to her father's home -- only to be told that he is away. Penny is suspicious of her stepmother's (Ann Todd) odd behavior, and is convinced that something is amiss. While searching around the house, Penny discovers her father's body, only to have it vanish before anyone else can see it. Is Penny's father really dead, or is she losing her mind?