A Gentleman's Game — Greg Rucka

When an unthinkable act of terror devastates London, nothing will stop Tara Chace from hunting down those responsible. Her job is simple: stop the terrorists before they strike a second time. To succeed, she'll do anything and everything it takes. She'll have to kill again.

Only this time the personal stakes will be higher than ever before. For the terrorist counterstrike will require that Tara allow herself to be used as bait by the government she serves. This time she's turning her very life into a weapon that can be used only once. But as she and her former mentor race toward destiny at a remote terrorist training camp in Saudi Arabia, Tara begins to question just who's pulling the trigger--and who's the real enemy. In this new kind of war, betrayal can take any form...including one's duty to queen and country.