Young woman Suzy looks out of the window of her apartment and witnesses a man murdering a woman in the apartment directly across from hers. Suzy is so traumatized by what she sees that she's rendered mute. Suzy is placed in the care of Dr. Trask, who alas turns out to be the man who committed the murder she witnessed.

Siamese twins, one timid and kind-hearted and the other reckless and sadistic, must make a decision on whether or not to allow an experimental surgery to have them separated even though one of them doesn't want to be split from the other.