Caledonia Styx is a captain without a ship, after a battle that nearly killed her. Pulled from the sea half-dead, she is saved by the Blades – renegade fighters who have escaped the clutches of Caledonia's vicious enemy Aric Athair.

She has one desire: to find her beloved ship and sisters so she can continue fighting Aric's fleet. But first she must persuade the Blades to join her on a rescue mission that will take them into the very heart of Aric's stronghold and even beneath the waves they sail...