The year: 2078 A.D. The location: planet Sirius 6B. The New Economic Block (NEB) and the Alliance are at war with each other over the mining of Berynium, the solution to the energy crisis on Earth. During the course of the war, the Alliance manages to create autonomous machines to attack the enemy (they're called screamers, and for good reason). However, these self-replicating and self-evolving machines have gotten more and more sophisticated with their tinkering and now pose a threat to all living beings on the planet. The evolution of the screamers reaches a point when a screamer is indistinguishable from a human.
Most of the action in Screamers revolves around the remaining humans fighting off the screamers. There is a great deal of suspense created in this movie, like in the books by Philip K. Dick (whose 1953 story Second Variety forms the basis for the plot), in not being able to distinguish human from screamer. There are also some thought-provoking moments when we are confronted with screamers that not only acquire intelligence that would enable them to pass the Turing test, but also feel human-like emotions (the natural consequence of evolutionary pressures). The setting is bleak and desolate and it works quite well for the theme of the movie. It's definitely worth renting if you're a sci-fi and/or a Philip K. Dick fan.