To mark the thousandth year of peace in the Empire of Concordia, the emperor's ship embarks upon a twelve-day voyage. Aboard are the heirs of the twelve provinces of Concordia, each graced with a unique magical ability known as a Blessing.

Except one: Ganymedes Piscero.

When a beloved heir is murdered, everyone is a suspect. Stuck at sea and surrounded by powerful people, odds of survival are slim. But as the bodies pile higher, Ganymedes must become the hero he was not born to be and unmask the killer before he ends up the next victim of their bloody crusade.