Killing Rain (2005)

In the fourth installment of Barry Eisler's John Rain series, the contract killer with a conscience is hired to eliminate a terrorist bomber but uncharacteristically botches the assignment when confronting his target face-to-face. In an exhilarating cross-continent chase, Rain and his partner, wisecracking Southern sniper Dox, follow the bomber through Asia without getting cut down themselves. Eisler unspools a plot full of warring secret government connections, cool spy paraphernalia, and vivid martial-arts sequences, plus an inter-spy romance between Rain and fellow assassin Delilah that leaves doubt as to whose side she's on. But what makes Killing Rain worthwhile is the story's mostly first-person perspective: Even robotic vigilantes can have a human side.