Point Blank. The Silencer Series, #5

After six months away in Detroit, Recker and Jones return their operation to Philadelphia. They're almost immediately thrown into trying to prevent a cop killing. They also come back to find things aren't quite the way they left them. One of the city's crime leaders tries to force Recker's hand, by using Mia as bait, in helping them take control of the city. Despite getting the cold shoulder from Mia initially upon his return, Recker works hard at freeing her from danger, taking her to the only place he knows she'll be safe.
It leads to a violent conclusion, one that finds Recker working with the police by his side.