Day of Doom

Amy and Dan Cahill have finally discovered the Vespers’ endgame. The Vespers have been collecting the 39 Clues in order to build a doomsday device that will destroy the world. Amy and Dan must use all of their skills and resources to stop the Vespers before it’s too late.
Along the way, Amy and Dan learn more about the history of the Vespers and the true power of the 39 Clues. They also meet a number of interesting characters, including a former Vesper agent and a group of international spies.
Day of Doom is a thrilling adventure story that will keep readers on the edge of their seats. It is a great read for fans of mystery, suspense, and action.