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" 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 thirteen 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 "13Stars". 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.