A number of years before a group of friends get trapped as they explore a cave. As time goes on and they get hungrier, Jeff (David Cannon) has the idea that they eat each other. They draw lots and unfortunately Ted (Ray Dannis) is chosen to have his arm cut off and consumed. Of course just as soon as the arm is cut off the rescuers arrive. Jeff and the others (sans Ted who is rather annoyed) decide to concoct a cover story and say they cut off Ted's arm to save his life...
Now a number of years later Jeff receives a horrific present in the mail, a severed arm! He finds out Ted has left the mental hospital he has been in and must plan a revenge. One by one the others are killed in various macabre ways, finally just Jeff is left with Ted's daughter Teddy (Deborah Walley), who has been helping him. Well Jeff thinks she has been helping him...
The twist is immense when it happens (though can be seen coming a mile off). The film is dripping with menace and suspense, assisted by a superb synthesiser led soundtrack. The only real criticism you can make of this film is that a little too much takes place in the dark and it is difficult to tell quite what is going on. Weird but great.