Together they discover that the self-replicating Screamers have begun to upgrade. They've taken human form and use infiltration to take the enemy off guard. Suddenly Hendricksson must question whether the people around him are human or not. And just as suddenly, the Screamers aren't just killing the enemy anymore.

Based on the 1953 Philip K. Dick short story "Second Variety," Screamers doesn't break any new ground. Still there are some nice touches, solid production values and an entertaining first half. As long as the Screamers remain unseen skimming just below the planet's surface, there's plenty of tension to keep the action moving.

Only when the Screamers take human form does the story get predictable. Trying to cross Alien with The Thing, Screamers pales in comparison. The second half of the movie degenerates quickly as viewers are left with nothing much to care about, and the fun of the first hour is completely lost.

Screamers seems almost afraid to rely on innovation and falls back into cliche when it could have covered new ground. Director Christian Duguay (Scanners II: The New Order) or his writers would have been better off following through with the technology-gone-haywire plot. Instead, they substitute actors for special effects by having the Screamers mimic humans, and the result is disappointing.

Despite these problems, Weller has one of his best roles in a long time as Hendricksson. He plays the part with humor and compassion. The only other actor to stand out is Lauer. The rest of the roles are underdeveloped, leaving the actors little to work with.