Not Exactly Dead (MI5 1/2, #1)

Richard Hugh, aka Triple-O Five of the unsung British agency nicknamed MI5 1/2, is happily making life miserable for bad guys and, when he has time, cultivating a reputation as a lady's man. But then the Americans get the notion that he's been marked for death by a notorious spy killer who has been bumping off spies belonging to an odd mix of nations. This would almost be business as usual, except that the Americans send Emma Chapman over to keep an eye on Hugh, in the hopes of catching the...