Here's another film that started extremely well before completely falling to pieces in act three. Sunshine is about the efforts of a scientist (Cillian Murphy) and his crew to launch a nuclear bomb the size of Manhattan into the sun in order to reignite it, as it is dying. Failure will mean that all human life will soon be extinct. It's a great premise for a movie, and for the first two acts, is a finely-tuned sci-fi thriller, as the effects of space travel take their psychological toll on the crew, and we wonder if they'll ever actually make it to the sun, given their diminishing air supply. In act three, the film fails, turning into a generic slasher movie once it becomes clear that a murderous stowaway is stalking the crew, and the film immediately stops feeling like a Boyle production. The fact that the villain is obscured from view for most of his appearances only makes the finale more frustrating to watch. Even if the very end of the film is still decent enough, the slasher film pay-off is terrible.