The game takes place in the mansion of the fictional Edison family: Dr. Fred, a mad scientist; Nurse Edna, his wife; and their son Weird Ed. Living with the Edisons are two large, disembodied tentacles, one purple and the other green. The intro sequence shows that a sentient meteor crashed near the mansion twenty years earlier; it brainwashed the Edisons and directed Dr. Fred to obtain human brains for use in experiments. The game begins as Dave Miller prepares to enter the mansion to rescue his girlfriend, Sandy Pantz, who had been kidnapped by Dr. Fred. With the exception of the green tentacle, the mansion's inhabitants are hostile, and will throw the player characters into the dungeon—or, in some situations, kill them—if they see them. When a character dies, the player must choose a replacement from the unselected characters; and the game ends if all characters are killed. Maniac Mansion has five possible endings, based on which characters are chosen, which survive, and what the characters accomplish.