Sydney's conscience struggles with her job, which too often asks her to work with criminals she'd much rather put away. She understands the logic -- the small fish versus big fish pragmatism -- but that doesn't make acceptance easier. Someone else is less conflicted and is assassinating APO's shadier contacts. Only the calling card of a black star with the number 13 in its center hints at the culprit. When it becomes clear that a highly trained -- and lethal -- vigilante organization is interfering with APO's missions, Sydney must put aside her empathy and help shut down the mysterious "13 Stars." But after Sydney herself is mistaken for a freelance terror agent, she worries that the mistake is not so far from the truth. And now that she's marked, both her cover and her welfare are in immediate jeopardy.