YA. Follows: Ingo. Sapphy, Conor and their mum have moved away from the cottage by the cove - away from the memories of their father, who disappeared two years ago - to the nearby town of St Pirans. Ever since, Sapphy has felt withdrawn and restless; she can't adjust to her new home and new life, and can't suppress the memories of her father and his mysterious disappearance. Unhappy in the world of Air, Sapphy finds herself increasingly drawn to the underwater world of Ingo and to her Mer friend, Faro. There she makes new friends: Faro's powerful, wise teacher, Saldowr, the dolphins, a whale and even sharks. But Ingo is becoming a more dangerous place. Although Conor senses this and pleads with Sapphy to stay away from Ingo, he cannot get through to her. And as Ingo grows in power both Sapphy and Conor are called to its depths to take on the might of Ingo's tides!