A fantasy game and reality collide for students when the aliens invade a campus to steal a lethal biological substance. Things become even worse when an alien is exposed to the toxin and becomes a mentally unstable rogue.

The theft of an Indian object provokes disgust from Ironhorse. But it also garners the aliens' interest, as it holds something that belongs to one of their ancient war machines.

To better understand their problem, the aliens begin abducting humans to learn the secret of their immune systems.

After a pregnant woman is possessed by an alien and gives birth, the child becomes the focus of a search as it may offer an immunity to Earth's bacteria.

Ironhorse must deal with a mistake that no soldier wants to make: the killing of an innocent civilian.

The aliens infiltrate the illegal drug trade in order to circulate a narcotic that will turn humans into violent killers.