'Science Fiction' The Aurum Film Encyclopedia:

The film follows the only man surviving the 'Effect', a scientific project which he helped to create that has gone drastically wrong and has caused the disappearance of the worlds populace. We follow him into insanity, from which he is rescued by apparently the only woman left living. They get together and become close friends and lovers, until another survivor, a strange and violent man appears. The woman is torn between the two, and the men fight for her. We discover that the reson these three have survived is because they were on the very point of dying at the time of the Effect. Come the end of the film, the Effect is about to happen again, prompting the hero to try and rectify it and.....well, I won't spoil the end for you. It's definately one of the best appocalypse films around, and I highly recommend it.