The height of Roman power. The greatest army the world has ever known – or, at least, that it remembers. Far down in the depths of the ocean, the remains of another power still survive, desperately eking out an existence. History has many secrets, and none more so than the mission of a certain Roman fleet, long lost in the murk of time.

When a private militia's rookie zombie hunters send out a distress call, it's up to the Rangers to cross The Wall and bring them back as well as uncover the truth about a terrifying new breed of zombie.