A surprising twist brings Amy and Dan back to New England for their first mission on U.S. soil since the beginning of the Clue hunt. But being close to home is anything but a comfort. The siblings have learned that there's a mole in the Cahill organization . . . and the traitor is one of their closest confidantes. However, this betrayal is overshadowed when Amy and Dan make an even more devastating discovery: the truth about the Vespers' real plan. Burdened with this terrifying information, Amy and Dan are forced to ask an impossible question: Is it more important to save the hostages. . . or stop the Vespers?