The monster is never to be lightly dismissed. It lies at the dark, secret heart of all horror movies. This time the monster is on a prison space station. Once again, all that stands between the world an a very large, unkillable creature drooling music from retractable jaws is the indomitable Ripley. Ripley is again played by Sigourney Weaver, her head shaved this time, but her resolve as firm and unwavering as ever. If you recall, in Aliens (1986), Ripley escaped LV-426 after blowing up the big nuclear-powered atmosphere processors, thereby destroying the alien beings that had taken over the planet. Now no sooner has her spaceship set down on the orbiting space station, than another pesky alien is at it again.

Just to be up to the ante a bit in the third installment, Ripley heads into battle without the high-tech weapons that have aided her in previous encounters with the alien. She has only her wits – not to mention all the machinations and wizardry that are the hallmarks of Hollywood megabudget action moviemaking – to rely on.

Originally, Renny Harlin of Die Hard 2 fame was sought as the director of Alien 3. When Harlin dropped out, a New Zealand director named Vincent Ward was attached to the project. Ward had made a visually stunning sci-fi film called The Navigator. On the plane to Los Angeles, however, ward decided he didn't like the existing script that had Ripley challenging the alien on a prison planet. When he got to L.A., Ward apparently convinced everyone that it would be better if Ripley's spaceship crashed into a lake on top of a floating monastery. "It sort of flies in the face of other Aliens," Ward asserted.

To much so, apparently The next thing, Ward and Fox had "amicable" parted company, and Alien 3 was back to the original script, with a new director – untried video whiz David Fincher, whose chief claim to fame was seeing Madonna through her Vogue video. The movie was shot in London where the budget apparently exploded out of control (it is rumoured to be anywhere from $60 million to $80 million). The plug was finally pulled and production completed on sound stages at Twentieth Century Fox. There were fights over everything from the script and the spiraling costs, to the movie's ending. Fincher who is 27 years old and directing his first feature film, concedes the whole experience was a nightmare. Weaver, however, is optimistic that the finished film was worth the agony. "It really stands on its own as a brilliant Alien picture, very unusual and very provocative," she told Premier magazine.

The original Alien was the brainchild of a couple of science fiction writers, Dan O'Bannon and Ronald Shusett. Their idea was simple enough: Instead of a haunting a house, make it a haunted spaceship. And rather than the creature coming from the black lagoon, have him come from outer space (a concert that proliferated during the 1950's in movies such as the aptly titled The Terror From Beyond Space).

What set apart from previous monster movies was the simple fact that this time someone chose to spend some money on it, and pitch it to a wider audience. "What Alien was," says director James Cameron, "is a very upmarket version of a B-movie."

It was immeaurably aided by the direction of the then unknown British filmmaker Ridley Scott, and, perhaps more importantly, it benefited form set and creatures designs by the artist H.R. Geiger. Geiger provided the film with a ruggedly industrial otherworldly look that has been imitated by countless other movies. Lance Henriksen, the actor who appears in both Aliens and in Alien 3, believes that it was Geiger's genius that is most responsible for the success of the movies.

"He's the kind of artist that's got his own world going," Henriksen says. "If you really got into his paintings, it's like being on another planet. They have a fundamental necro-sexual thing to them that is an anchor to the films . . . It's sex and death coming together in the same design."

K-Y Jelly was employed for the alien creature's drool, and shredded condoms provided the ghastly looking jaw tendons. The fully grown creature was portrayed by a seven-foot-two Masai tribesman from Africa who was studying in London.

Alien provided a 30-year-old actress named Sigourney Weaver with her first movie role. The patrician daughter of Sylvester "Pat" Weaver, the NBC television pioneer, Weaver was no one's idea of an action heroine. In fact, at that point, a female survivor in an action-oriented sci-fi horror movie was all but unheard of (although John Carpenter had introduced to horror audiences the heroine-who-survives in the person of Jamie Lee Curtis the year before in Halloween.)

Weaver said she would never do a sequel. Six years later, with James Cameron on board as writer and director, she recalled of the sequel talk. "and I think it took someone as a confident as Jim, with a different vision from Ridley's, to attempt it."

What Cameron envisioned was a meaner, scruffier, less elegant, more action-packed Aliens. It feature gung-ho marines returned to the planet where the creature was first discovered, determined to kick a little alien butt. For all the critical accolades the sequel received at the time, Aliens is not as good as the original. It is more of a "lost patrol" picture than it is a variation on the haunted house theme of the original. Cameron, fresh from writing the script for Rambo: First Blood II, could not quite shake off Rambo when he came to Aliens. In his hands Ripley became a kind of "Rambolina," whose violent impulses emerge when she has to save a little girl from what turns out to be, literally, the mother of all aliens: "Let her go, you bitch!" became the most quoted line of movie dialogue of the summer of 1986.

Curiously, the success of the Alien movies has done little to encourage other American filmmakers to experiment with the genre. The monsters still lurk in the basement, at the bottom of the black lagoons, in the haunted houses, and on spaceships. They are the nightmares in an otherwise dreamy moviegoing experience. Every so often it is necessary to let them out. Be careful. That monster drooling K-Y Jelly on Sigourney Weaver's shaved head is actually the enemy inside us all – struggling to get it out.