While responding to the riot in Arkham Asylum, while crossing the bridge GCPD forces were ambushed by T.O. Morrow's mutant army as they spread from the Ace Chemicals chemical factory, resulting in a vicious standoff as the GCPD attempt to make their way through the blockade of cars to the west blocking them from entering Arkham Island while also fending off attacks from T.O. Morrow's clowns and chemoid mutations from the east.