The head of the US National Security Agency is assassinated in a spectacular set-piece killing at Heathrow. A Pakistani airport employee and his family are found murdered in their council house in Uxbridge. In New York, a fashionable Upper East Side osteopath receives two postcards of the Empire State Building from someone called Karim Khan, one posted in Turkey, the other Iran. A group of migrant workers, including Khan, en route from Afghanistan to the EU, is brutally gunned down in Macedonia. The quest to find the link between these apparently random events is pursued by Robert Harland, with the help of Isis Hernick a young female officer of MI6, as he finds himself catapulted back to a life he hoped he had left behind for good.