A mysterious object enters the airspace of a military base in California going at a tremendous rate of speed. A team is sent out to investigate. It turns out to be one of the Viking landers from that we sent to Mars. How did it get back to Earth? Why is it here? Is there a big nasty alien that's going to end up popping out of our chests if we touch it? While the last question is a bit of a joke relating to the obvious Alien (1979) influences on Lifeform (aka Invader), it's no secret that the film involves, well, an alien lifeform. What seems to be more of a secret is the film's existence and the fact that it's pretty good.
An obviously low-budget affair, writer/director Mark H. Baker overcomes this limitation with a smart, well-constructed story, plenty of sci-fi horror tension, and fine performances (including from an amusingly young Ryan Phillippe). A lot of the budget appears to have been spent on building the Viking replica, the costumes/military accoutrements for the human cast, the creature costume and special effects. It was money well spent. The effects are amazing for such a low budget film. The creature costume is as good as most big studio efforts, the Alien-style cocoons and eggs are well done, and there is a great, visceral autopsy scene.
Except for exterior location, Baker wisely keeps all of the action in a nondescript government facility. "Nondescript" may not sound very attractive visually, but it's believable. That's how government facilities look. Besides, Baker is skilled enough to make it interesting visually. The bulk of the plot is divided into two modes: (1) figuring out what the Viking lander and then the alien are doing there, and (2) "monster" chase and attack scenes.
Baker gives us fantastic sci-fi writing for both. We have a team of bright, multi-dimensional scientists examining the lander from a "hard science" angle, with dialogue that's not gobbledy-gook yet that's easy enough to understand. They propose intelligent theories and make intelligent moves. As the military becomes more involved and we begin to enter more of an action/horror sci-fi mode, Baker doesn't have his characters leave their brains at the doors. They develop an Alien-like sulfur detector to find the monster, and they have insights into its behavior that help them.
Still, the material is very suspenseful at times, and it is consistently captivating. There are clever subtexts. One is keyed to an important piece of dialogue--"Why are we exploring space if we're just going to blow-up every lifeform we come across?" Even though there is little reason to believe that the alien has ill intentions, most of our protagonists assume that it does, and they all assume that it at least poses a great danger to them in the form of unwittingly transmitted viruses, for example. They go so far as to issue a quarantine and consider drastic worst-case-scenarios and options. Baker seems to have a pessimistic view of human tendencies in the face of the unknown, and probably deservedly so.
Although there are some flaws with the film (otherwise I wouldn't have subtracted two points), including strange moves by characters, such as one wearing a face mask to guard against biological contamination and another standing a foot behind and not wearing a face mask, Lifeforce is unusual (such as its strange but refreshing nihilistic endingapparently, fortuitously precipitated by budget limitations) and well worth watching.