It is the 14th century and Grenada is again under threat thrusting thirteen year old Sultana Ara and her cousin Layla again into danger. As Ara and Layla sail down the Grenadian coast to raise tribute for the Castilians, a magical and mischievous Jinn appears to cause trouble. And worse, a young, arrogant Venetian boy, Tomas, is aboard their ship. The Jinn issues a mathematic challenge to the young people; the stakes are high and none can afford to lose. Ara and her friends must use all their skill to protect themselves and Grenada, but will it be enough to defeat a Jinn? And what happens to the Jinn if he loses?