The Forest (1982)

Two campers Sharon and Teddy are terrorized in the deep dark woods of the California wilderness by a cannibalistic knife-wielding madman. Teddy is killed but Sharon manages to escape. That same night their boyfriends, Steve and Charlie, take refuge in an old cave to protect themselves from the storm.

There they meet the killer an old man wearing a beat up old baseball cap named John. He tells them the story of how he walked in on his unfaithful wife and her lover. He killed them both, and gathered his two children and ran off into the forest. Unfortunately, his kids got sick and they commited suicide. Since then, he has developed a taste for human flesh and will kill anybody who trespasses on his territory. The next morning, Charlie is drowned and prepared for the killer's breakfast. He then goes looking for Sharon, who has, unbeknownst to him, teamed up with the ghosts of his two dead children. The maniac chases Sharon but just as he's about to kill her his ghost kids save her. He runs off into the wilderness to find the wounded Steve, who has broken his leg. Can Sharon save her boyfriend in time?