One Shot One Kill

Detective Sergeant Dan Ferris is close to burning out.
Victims are turning up beaten, bodies mutilated, and his relationship appears to be on a downhill slide. His nephew, Coleman Armstrong, is on a dangerous undercover assignment, and a sniper has the city on edge.
When Cassie Hart links Dan's girlfriend, Mia, with the kill sites, he wonders if Mia's past has caught up with her. Rogue cops infiltrate the police force, and lives are threatened.
Who can Ferris trust as the clock ticks before the sniper strikes again?