Aiden, a lowly deckhand, has always wanted to swear the Sea Oath to Ethan, the captain's adopted son. On his eighteenth birthday, his Tide Mark appears, he begs Ethan for the oath, but is publicly rejected, and his mark fades. Then Ryan, the captain's wild blood son, returns. He taunts Aiden at first, but protects him in secret. The witch Riley reveals Aiden has a second oath-bearer, and his mark glows brightest near Ryan. Ethan, seeing them grow close, regrets and confesses. Caught between the one who broke him and the one who never let go, Aiden is trapped in a brother's war for his heart.
