Artemis City has been at peace long enough that most of its residents have forgotten what war looked like. Then a warship from an earlier era is discovered by the military — and aboard it, hundreds of dormant SlaveGears: combat mechs from a conflict everyone would rather forget. Two of them, Hound Dog and Rising Dog, are transferred to the police for experimental use. The manned test of Hound Dog barely begins before disaster strikes: the ship's master computer, Omega, activates remotely through military channels, freezing all city functions and commanding every SlaveGear on its network to eliminate threats — which, to Omega, means everything. Rising Dog activates on its own. Research facilities are destroyed, and a mech disappears into the city streets. The police issue an emergency order: Hound Dog, abort all tests, converge on the city. Terminate Omega.