Our Kind of Traitor by John le Carre (used)

Britain is in the depths of recession. A left leaning young Oxford academic and his barrister girlfriend take an off-peak holiday in the Caribbean island of Antigua. By seeming chance, they bump into a Russian millionaire called Dima who owns a peninsula and a diamond- encrusted gold watch. He also has a tattoo on his right thumb and wants a game of tennis. 

What else he wants propels the young lovers on a tortuous journey through Paris to a safe house in the Swiss Alps , to the murkiest cloisters of the City of London and its unholy alliance with Britain's Intelligence Establishment.