The Wreath of Poseidon is a story of betrayal and the struggle for control over the forces of magic and scientific knowledge. Kassandra's a bookish teenager with an extreme fear of water. She comes from the sea, but she spends most of her life far from it, an exile sent inland to grow up, betrayed by her own family and fated for slavery. She's caught between a murdering king, a governess who's been trying to kill her since she was four, and river witches who spy on her through the plumbing. She's managed to stay alive so far, but on her thirteenth birthday, Kassandra's world tumbles into the abyss. She cries for the first time in her life, and not just a tear. She discovers that her mother and father didn't abandon her, and there's more to her governess than the tyrannical facade.