Slumber Party Massacre III 1990 part 4 the end

The opening credits show a montage of photos. The final image shows a still black-and-white photograph of an unknown man with a young boy. Then, it cuts to a group of friends playing volleyball at a Los Angeles beach. Jackie is a high school senior throwing a slumber party that night. When they leave the beach, one of the girls, Sarah, gets into her car and is brutally drilled from behind the seat. Jackie is driven home by Frank, her love interest. Inside her house is Morgan, her next door neighbor, who thought it was an open house. An apparently nervous Morgan then leaves. That night, Jackie's friends, Diane, Maria, Juliette, Janine, and Susie, arrive for the party. When two of the girls playfully perform a striptease, Frank and two other boys, Tom and Michael, scare them. Jackie angrily tells the guys to leave. Meanwhile, a weirdo from the beach two girls spotted earlier spies on them from outside.