The Gilgamesh Conspiracy (Gerry Tate Book 1)

A sensitive political deal codenamed Gilgamesh, goes wrong at the beginning of the Iraq war.
One by one the people who know about it are eliminated, except for two: Ali Hamsin, an Iraqi government translator who is kept hidden in Guantanamo Bay and Gerry Tate, a British intelligence agent. She is in prison for murder.
Years later Ali Hamsin says he will reveal his secrets, but only to Gerry Tate. Their captors decide to bring the two together and keep them both alive for a short while longer, but Gerry Tate is a dangerous woman to set free.