10) Saw (2004)
The Story: Two men awaken chained to pipes in a dirty, disused bathroom. A dead body lying between them holds a tape recorder, through which they learn that they are prisoners of the sadistic Jigsaw killer, who likes to play games with his victims. One man, Adam, is told to escape the bathroom, while the other, Lawrence, is told that he must murder Adam or else his wife and daughter will be killed.
The Twist: After Lawrence saws his foot off and shoots Adam, one of Jigsaw’s cronies enters to kill Lawrence, but is bludgeoned to death by a heavily bleeding but still conscious Adam. Lawrence crawls to get help, leaving Adam still shackled. The dead body, which has been between Adam and Lawrence for the entire movie, suddenly arises to reveal itself as the Jigsaw killer, John Kramer. When Adam tries to shoot him, John shocks him and knocks the gun away. He then seals the door and leaves Adam to die in the dark.
Why It Sucks: For most of its running time, Saw is a nauseating but compelling horror film that uses its small setting to great effect. However, having a corpse suddenly rise to life is a strange twist that comes out of absolutely nowhere and insults the intelligence of the two main characters. It seems strikingly illogical that neither Adam nor Lawrence would have scrutinized the body to check for signs of breathing or movement. If there had been some sort of hint at Jigsaw’s presence in the room with the two men earlier in the film, his ultimate unveiling could have been a great twist, but because it comes out of nowhere and holds basically no significance to viewers who’ve only gotten to know Adam and Lawrence in the film, it ends the tense, atmospheric horror flick with an undercutting whimper rather than a bang.