Aiden, the lowest deckhand, has always dreamed of the Sea Oath with Ethan, the captain's adopted son. On his eighteenth birthday, his Tidal Mark appears, but Ethan rejects him, nearly destroying his mark. Then Ryan, the captain's wild blood son, storms into his life, taunting, teasing, then fiercely protecting him. He wakes his mark, and makes him feel alive. The witch reveals Aiden has a second Sea Oath partner, but Ethan regrets and chases after him. Now trapped between Ethan's repentant love and Ryan's possessive devotion, Aiden's heart is torn. When Ryan catches Ethan holding Aiden from behind, the brother war reaches its breaking point...
