Grade • B+

DVD • Science-fiction fans were justifiably excited this summer with the idea that director Ridley Scott might be returning to the futurescape of his 1979 classic "Alien." "Prometheus" teases us with the possibility that it will answer some of "Alien's" mysteries, but instead it launches into some mysteries of its own.

With an epic structure reminiscent of Stanley Kubrick's "2001: A Space Odyssey," "Prometheus" mostly focuses on a survey ship arriving at a planet where an optimistic anthropologist, Elizabeth Shaw (Noomi Rapace), hopes to find clues to extraterrestrial hints to humanity's origins. The mission gets complicated, and lethal, when the ship's service robot, David (Michael Fassbender), seems to be following his own mission.

Scott's action set pieces are powerful, but the links to "Alien" sometimes weigh down the story. Extras include a commentary by Scott and plenty of deleted scenes for when he makes his inevitable "director's cut."