Summer 1941. Four violent deaths, French double agents, an escalating fraud case - DCI Frank Merlin sets out on his most complex case yet. War rages across Europe. France is under the Nazi thumb. Britain has its back to the wall. In London, Scotland Yard detective Merlin investigates a series of disturbing events - a young girl killed in a botched abortion, a French emigré shot in a seedy Notting Hill flat, a mysterious letter written by a British officer, gunned down in Crete. Chasing evidence spanning Buenos Aires, New York, Cairo and Occupied France, Merlin and his team are plunged into an international investigation of espionage, murder, love and betrayal.