Mary Elizabeth Griffiths has faced hard things before, but nothing like losing her father to the sea. Captain Bill insists he's gone for good. Everyone does. Everyone except Mary, who knows in her bones he is still out there somewhere and she is determined to bring him home.

It is 1911, on the gloomy Oregon Coast, and when strange, distant cries echo from the waves, Mary is drawn to the shore and swept into a hidden world beneath the ocean, a realm of mermaids, sea serpents, and kingdoms on the brink of war. There, she meets King Anko, a legendary sea serpent who believes Mary's arrival is no accident. But the Queen of the Mermaids, bound by old-fashioned ways, sees Mary as nothing but a defiant child.

To rescue her father, Mary must navigate royal rivalries, outwit a wicked sea magician, and confront parts of herself she has not yet understood. If she fails, the ocean's battles may swallow her whole.

For anyone who has ever felt the pull of the sea and the promise of something hidden beneath, The King Beneath the Sea is a bold, heartfelt reimagining of L. Frank Baum's The Sea Fairies, the forgotten underwater Wizard of Oz, a timeless adventure about grief, grit, growing up, and a stubborn girl who refuses to give up.