Vengeance (The Sin Trilogy #1)
A.J. Scudiere

Three years ago, Lee Maxwell made the same error. His wife and daughter paid for his mistake. In a haze of booze and regret, Lee disappeared.
Now, Owen Dunham is following the trail of the ‘Grudge Ninja’-only all his evidence is false and the profilers can’t get their heads around anything except the obvious fact that the Ninja is extracting a deadly revenge for an old wrong.
As the Ninja gets bolder and far more dangerous, Owen is forced to recognize that he hasn’t always made the right decisions–he’s spent far too much time trying to be right. Even as he questions whether bringing in the ninja is the right thing to do, the voice in the back of his head is telling him that it will make his career...
From the author of "Resonance".