General Charles Ferguson, Commander of the British Prime Minister's private hit squad and adviser to the new president of the United States, has been given a disturbing recording from Afghanistan, on which the murders of American Army Rangers and a British medical team are recorded. About half of the Taliban force voices on the tape are British. One authoritative voice is Irish; code name: Shamrock.

Shocked that one of their own could be responsible for a massacre, General Ferguson tasks Sean Dillon with hunting the traitor. But even as Dillon goes to war, the war is coming to him...