The day before Kae and Aqeara's royal wedding, a random attack on Avalon's port leaves the kingdom reeling with loss. The two queens learn of similar attacks in other kingdoms, including Aqeara's underwater home.

On a mission to hunt the individuals behind the attacks, Queen Kae and Queen Aqeara replace their crowns for tricorn hats and blades. They rally their crew and set sail on a dangerous adventure where secrets swirl to life and truths threaten to overcome them.

Ruff never expected a happily ever after, but just as one was within his reach, it had been ripped away. When Captain Kae approaches him, Ruff sets aside his grief and joins his close friends on another harrowing journey. But the weight of a missing piece of his heart might just drown Ruff out at sea, where he first gave his heart away.