 A third murder in the last two weeks is reported over the television, and police confess they have a psychotic madman on the loose, preying only on live-in nurses. One dark stormy night, Nurse Stella Crosson (Dana Wynter) and Nurse Betty Ames (T.C. Jones) are tending to their employer, a man with a heart condition who resides in a creepy old mansion just outside of town and needs constant attention. A phone call from the murderer informs the women that he knows they re alone, and intends to pay them a visit before the night is over. Checking to make sure all the doors and windows are locked, Stella finds that she overlooked a basement window, a mistake that might prove all too costly.