A top-secret military biological weapons research lab, White Flag, is breached. From inside, it's lock down. There's no explanation, no communication, and no access. The job of investigating White Flag falls on the young and beautiful Dr. Susan Cole.

Assembling a team and exploring the deserted site, Cole informs the Pentagon that they are dealing with an alien microbe - the result of an experiment that went wrong. Ordered out of White Flag, the team heads for the airlock. The path is blocked by six-legged creatures that spit acid. Weapons are ineffectual - each time they blast a creature apart, it reforms and attacks again. The alien microbe is alive and evolving, each new creature smarter and stronger than the last.

New orders send the team on a suicidal mission: set off a neutron bomb buried in the bowels of the complex. Fighting their way to the bomb, Cole loses team members, one by one, until she’s left alone to neutralize the threat and ensure the safety of the world.