Secret Keeper - Knight Agency, #1

"We are the thin red line which separates order from chaos."For a thousand years, the Knight Agency has secretly kept watch, protecting mankind and society from innumerable threats. For five of those, Agent Jane Browne has already played her part in this game as well. But now, a threat is aimed at herself and the few she cares about. The mysterious 'M' might find out it's not a good idea to tease a Knight Agent in general - and much less of a good idea to tease Agent Browne in person.