Boston, 2009: a maverick police detective must work together with a microbiologist to capture Adrian Dunn, his former partner. Dunn went bad and ended up imprisoned on the moon. There he was exposed to a deadly, highly contagious virus that turned him into a murderous mutant who's now escaped and returned to Earth. First he killed the detective's wife. Now, if he is not stopped, Dunn could wipe out all humanity.