The second book in the Realm series. Jason and Alex are off to the Caribbean for their next great adventure. Professor Humphrey is also on board. The twins make a new friend who helps them identify one of their kidnappers. She and Jason pay a surprise visit to Terrania which has a life-changing effect on both of them.When the ship is hijacked and Alex and the Professor are taken hostage, we discover that there are still some people desperate to find the map, and to use the data the professor is collecting to locate the treasure they believe to be somewhere in the depths of the Caribbean Sea.