The film is about the curse that hangs over the sleepy seaside town of Antonio Bay. It opens with John Houseman's creepy old seafarer spinning a ghost story round the campfire. As I say, it's a classic piece of storytelling. Fans of this movie will know its history: how it was re-shot, re-edited and re-scored in the space of a month. Hardly surprising, then, that the film hangs together as neatly as it does. The film we see is the result of the director being dissatisfied with the original finished product. That gives it a special succinctness and, at just shy of 85 minutes, it's swift and to the point. The chills are good, although the later violence belies the film's early, gloomy ambience. The Fog was shot largely at Point Reyes on Tomales Bay, north of San Francisco, and Dean Cundey's exquisite photography builds a tremendous amount of atmosphere.

The casting sees something of a reunion for repertoire Carpenter stars. Alongside Jamie Lee-Curtis (Hallowe'en), we have Charles Cyphers (Hallowe'en, Assault on Precinct 13), Tom Atkins (Escape from New York), Adrienne Barbeau (Someone's Watching Me!, Escape From New York), George 'Buck' Flower (Escape from New York, They Live, Village of the Damned), Darwin Joston (Assault on Precinct 13) and Nancy Loomis (Hallowe'en). It's especially nice to see Darwin "Wilson" Joston...allbeit without a gun.

Without question, the tense atmosphere built in the first half is not reflected later in the film. The Fog's only failing is that in the beginning it relies on the creepiness of the town's superstitions and on the growing menace that the stories might be true. The second half hangs on a frantic chase and an ending that seems...well, lacklustre. The second half simply doesn't live up to expectations formed by such a great opening. This is not to say that the film fails, because quite the opposite is true. You just sense that the mood was changed to satisfy preview audiences - particularly the "shock" ending. Which is a shame, because it robbed it of the five stars it might otherwise have scored. That said, I do think my childhood was the richer for those grisly sound effects as hook meets face, sword meets neck and, earlier in the film, spike meets eye. Classic stuff.

There's no question that fog is pretty frightening. Especially if water-logged corpses come out of it and slay townsfolk you consider to be friends. Nothing nice about that. The fog we see in John Carpenter's The Fog has its origins in real science. Though obviously the bit about corpses is embellished. The fog we see hanging over the sea stems from a process whereby cold, dry air carries over warmer water. The fog forms when the warm water evaporates, causing it to rise. It then cools and condenses. As for the thick, swirly fog we see oozing through the streets of Antonio Bay, well that's a different kettle of fish. You see, when warm, moist air flows over very cold earth and the air saturates (ie, the amount of water vapor in the air is the maximum possible at that temperature and air pressure), moisture condenses out of the cool air and forms fog. And that fog can be very dense. The MET Office will not comment either way on whether or not fog can drift under doors, move against the wind, or sustain the weight of corpses.