The Human empire, the United Protectorate, is at war with the reptilian alien race known as the Brelac. The Brelac's bloodthirsty onslaught brings forth the creation of genetically engineered Humanoid weapons called Reploids. These Reploids are the perfect weapons. They are the identical copies of Humans that have been captured, killed, cloned, and embedded with powerful psionic based abilities.They are untraceable as they blend into Human society. They are so believable that the Reploids don't even know that they are clones.

    Colin McKenzie is a second generation Reploid planted in the Protectorate military. When he turns on his commanding officer in an attempt to protect a pair of shipwrecked Brelac soldiers, he is captured and reprogrammed along with two other arrested Reploids to serve the government that they were originally created to destroy.

    A dark alliance between the Brelac and the separatist organization Vendatta looms over the Protectorate. The balance is upset when the traitorous Doctor Howard Fenlow, the sciientist who is the very creator of the Reploids, manages to produce a weapon powerful enough to bring the Protectorate to it's knees. And there are only three that can stop it.