Friday the 13th Part 2 (1981)

Months after Alice beheaded psycho killer/mother Pamela Voorhees at Camp Crystal Lake, survivor Alice is still traumatized because of the murders. But there is one problem: Mrs. Voorhees' son Jason never drowned and died, so he saw Alice behead Mrs. Voorhees. Jason finds Alice soon and murders her. Five years later, a camp counselor-in-training program begins at Packanack Lodge, right near Camp Crystal Lake. As teenagers in the program start snooping around Camp Crystal Lake, they start getting killed violently one by one.