In this James Cameron-directed sequel to the 1979 science-fiction horror film “Alien,” Ellen Ripley (Sigourney Weaver) reluctantly returns to planet LV-426 with a unit of space marines to investigate the disappearance of a terraforming colony. The only colonist they find is a young girl, whom Ripley takes under her wing. When the Aliens inevitably attack, Ripley and the girl duck into a duct. The duct spills into what looks like a trash room, apparently ventilating the trash room into the building or the building into the trash room. Or perhaps the whole building is trash, considering the Aliens have made quite a mess of the place. Near the end of the film, it is everybody into the ductwork, as they have only 16 minutes until a reactor blows. This ductwork not only supports a half-dozen people, but a couple pretty gnarly auto-aiming machine guns that fire nearly a thousand armor-piercing rounds into the creatures without harming the duct in the least. The sequence ends with Ripley and the girl riding the centrifugal fan at the end of the duct.