They traced the phone calls as coming from in the house. The police told Jess to get out, but of course she went upstairs and found the bodies of Margot Kidder and the woman with the glasses. She saw the killer's eye peaking through the wardrobe (that was creepy) and ran downstairs and locked herself in the basement with the killer banging on the door.
He stopped, and a few moments later Peter (her boyfriend) appeared at the basement window and smashed the glass to get in.
Next thing we see is the police arriving and kicking in the basement door to find Jess alive having killed Peter, assuming him to be the killer...
The film enRAB with a shot of the house. You hear a whisper, and then the phone rings...