The World's Fair, Belgium, 1958. Freshly arrived is mild-mannered civil servant Thomas Foley, here to ensure the British contribution - a pub called the Britannia - is no national embarrassment. But it is the height of the Cold War and the Fair is a hotbed of paranoia and deceit.
With his superiors fearful of leaked secrets and defections, Thomas is spied on and directed to spy on others. Thrust into a game he barely understands, distracted by a romance which tests his marital and family loyalties to their limit, Thomas gamely tries to do the right thing - if only someone will tell him what that is . . .