Bestselling author Katherine Webber pens a highly-anticipated and swoonful new spin-off to the Sunday Times bestselling YA romantic fantasy series, Twin Crowns. Bursting with epic adventure, romance and humour on the high seas. Someone is making waves … Captain Marino Pegasi. Wedded to the sea. Immune to love. Until now … Captain Marino Pegasi is never happier than when he’s exploring the oceans. But when his beloved sister, Celeste, falls gravely ill, he is forced to go on a desperate search for a cure. Little does he know that in his search he will find so much more lying beyond the horizon. Does Marino’s fate truly lie in the hands of a bewitching, mysterious mermaid …?