Twelve-year-old Tom has grown up on the decks of The Salty Crown, the ship captained by his father-a legendary but slightly washed-up pirate known for raiding merchant vessels that fly the banners of greedy surface kingdoms. Tom's life is all salt spray, sword practice, and tall tales of buried treasure, until the day their crew is hired by a mysterious young prince to hunt for the lost Crown of Tides-an ancient artifact said to grant command over the seas.