Hans and Feetz had become used to spending their lazy summer days sailing in the familiar waters around Pender Harbour and exploring the many nearby islands. But a freakish storm was about to change everything. Shipwrecked and marooned on a phantom island, the two spirited boys discover the fascinating subterranean kingdom of Diluvea. Together with a Diluvean team of mighty men and scholars, Hans and Feetz set out on a quest to recover a precious, ancient relic – the Diadem – believed to possess the power to deliver perpetual light to this underground world. But seven deadly perils stand in their way. In facing these challenges, Hans and Feetz lead you on an unforgettable adventure full of mystery, danger and heroism. Will the return of the Diadem bring the incomparable gift of light the Diluveans anticipate, or will it bring darkness and destruction? The boys and their companions must use all of their combined skills and courage to try to save this hidden world and rescue its people.