The most wonderful and horrible thing about film franchises is that where they begin and where they end up usually have little to do with one another. Take the Alien series, now collected in an exhaustive, smartly assembled, nine-disc box set. (Smartly assembled, that is, apart from the designers' apparent ignorance of the word "tetralogy.") The product of a chance collaboration between a bunch of guys working on a never-to-be-filmed version of Dune and a commercial director with only one feature under his belt, Alien has led to three markedly different sequels–each, like the first, a receptacle for anxiety about technology, corporate ethics, military might, and the human body. Released in 1979 at the tail end of a wave of science-fiction films, Ridley Scott's Alien filled the future with a monster borrowed from the oldest reaches of the psyche, a pitiless creature dedicated only to devouring and reproducing, designed by H.R. Giger for maximum Freudian implication. Scott has said he set out to make a cross between 2001 and The Texas Chainsaw Massacre, and his wish is reflected in the result: a nightmare set in the chill of a disappointing future. On one of the many supplemental documentaries spread across the box set, Alien: Resurrection screenwriter Joss Whedon comments that each sequel is notable for its failure to live up to the original. Some would argue that 1986's Aliens more than lives up to Alien, but Whedon is still partially right. Sequels are defined by the expectations of pleasure created by their sources, and most of what makes the Alien series so compelling is the way it skirts those expectations. The core elements remain the same from film to film, as does the anchor, star Sigourney Weaver. But unlike, say, the conservatively programmed James Bond series, each Alien film offers a distinct directorial vision, and each plays out as a variation on existing themes rather than a chapter in a longer saga. For James Cameron, Aliens was a chance to portray a hard-won motherhood in the form of an old-fashioned war story, and the combination worked remarkably well, thanks to the director's trademark psychological and physical intensity. In 1992's Alien 3, it's possible to see a lot of the director who would go on to make Seven and Fight Club. Making an ill-starred debut, David Fincher took control of the film after the studio scaled back the ambition of the original project. In Fincher's hands, Alien 3 became an excursion into nihilism on a dilapidated, claustrophobic prison planet populated by celibate fundamentalists. Any sequel that begins by not only killing off the endearing survivors of its predecessor, but also subjecting one to a gruesome autopsy, has a lot from which to recover, and Alien 3 never quite pulls it off. It does win points for stylistic bravado and the courage to take the series' darkest turns, but it loses those points by being unforgivably dull. (But then, based on the production stories from Alien 3's surprisingly frank making-of documentaries, it's a minor miracle that the film is watchable at all.) The most recent and weakest of the batch, 1997's Alien: Resurrection plays like a collection of intriguing, half-formed ideas joined to the incongruous imagination of French fabulist Jean-Pierre Jeunet. Still, when considered as part of a whole, and even with Winona Ryder as a robot, Resurrection maintains an odd integrity. It's perfectly in keeping with a series that began by simply putting a monster on a spaceship, then gave itself the creative freedom to explore what that monster and that spaceship really meant. Stumbles and all, the series makes for a box set whose scope matches the heft of its packaging.