After a siren attack USS Constitution and HMS Victory are transported to the world of Remnant. This new world is dangerous and there are no guarantees; however, these girls are warships, who more than left their mark on history. Now they will do so once more and may god have mercy on those who stand in their way.

There is an exception to every rule. Four brothers have hidden themselves from the law for decades. After a bad encounter in Atlas these bothers bent on the genocide of the entire species of Grimm have found themselves increasingly involved in a game of chess between two beings they know virtually nothing about and are determined to achieve their goals by any means necessary.