He immediately contacts his friend, Doctor Ray Sanders, and the two discuss an incident five years before when, as part of a group of cave explorers, they were trapped by a cave-in.

In order to avoid starvation, the group had cut off the arm of one of their fellow cavers, a man named Ted Rogers, planning to eat it.

However, moments after doing so, the entire group was rescued and they quickly concocted a cover story for the authorities, saying that Ted had lost his arm in the cave-in and concealing that they had cut it off with a knife.

They attempt to trap the killer, who they believe is Ted, but Mark has his arm ripped off after being pushed from a cliff with a rope around his wrist.

[1] The film was released on VHS and DVD by various companies, the legality of which pertaining to official licensing rights is in question.