- "In a game of international intrigue, you can't always play by the rules."
- — Tagline, from the front cover
While attending an international summer school at England's Oxford University, the Hardys learn just how much times have changed. Frank's roommate, Pyotr Zigonev, is the USSR Junior chess champ, and he had become a pawn in an international power play. But just as the boys rally to Zigonev, they discover that the CIA has joined forces with the KGB.
The American and Soviet spy masters are out to foil a master of terrorism, and Frank and Joe and Zigonev are caught in the middle. One false move and they'll lose the ultimate game -- a danger-packed contest played out in the cold gray shadows of Stonehenge.