BLACK CHRISTMAS

An unseen man climbs the exterior of a sorority house during a Christmas party and enters the attic. The house phone rings, and sorority sister Jess Bradford answers, discovering an obscene call from a previously known caller nicknamed "The Moaner". The caller rants in strange voices about someone named "Billy" and speaks vulgarities before threatening to kill them. Upset, a younger student, Clare Harrison, goes upstairs to pack, where she is attacked and asphyxiated by the intruder.

The next morning, Clare's father, Mr. Harrison, arrives, concerned she missed a train. Housemother Mrs. MacHenry offers to help search for her. Jess tells her boyfriend Peter Smythe she is pregnant and plans to have an abortion, angering him. Meanwhile, Mr. Harrison and sorority sisters Barb Coard and Phyl Carlson try to report Clare's disappearance to Sergeant Nash, who brushes them off until Clare's boyfriend, Chris Hayden, storms in and demands action.

That night, a search party gathers to find Clare as well as Janice, a young girl who has gone missing nearby. Volunteers locate Janice's dead body in a nearby park. Meanwhile, Mrs. MacHenry discovers Clare's body in the attic but is killed by the intruder with a crane hook. Jess receives another obscene call and decides to involve the police. Lieutenant Fuller arrives with a lineman to trace the call.

After Fuller leaves, an inebriated Barb suffers an asthma attack and retires for the night. Christmas carolers distract Jess while the killer enters Barb's room and murders her with a glass unicorn figurine. Another call from the intruder echoes parts of Jess's argument with Peter. Fuller reports the trace failed, and suspicion briefly falls on Peter. Jess and Phyl lock the house, but Phyl is killed after finding Barb's body.

A subsequent call is successfully traced, and Nash instructs Jess to leave immediately, realizing the calls are originating from within the house. Jess finds Barb and Phyl dead and glimpses the killer through a door crack. She flees to the basement and locks herself in. Peter breaks in, and in a panic, Jess kills him with a fire poker. Police arrive to find her barely conscious beside his body, assuming he was the killer.

Believing the danger over, police leave Jess sleeping in her bedroom with an officer outside. From the attic, the killer's voice is heard, and the hatch opens, while Clare and Mrs. MacHenry's bodies remain undiscovered. The house phone rings once more.