Murders are on the rise in Philadelphia-but no one seems to mind because the victims are all fugitives with histories of heinous sex crimes against women and children. Worse for Homicide Sergeant Matt Payne, the main suspect is leaving evidence for police to find. But when copycat killings start popping up due to vigilante groups dealing out their own justice, Payne must find out who's behind the chaos before the violence overtakes the city.

In the aftermath of a brutal attack on his Philadelphia lawyer daughter, Wyoming sheriff Walt Longmire, aided by his best friend, Henry Standing Bear, team up with the Philadelphia police in a determined search for answers.

Investigating rumors about a new partnership between the Mexican drug cartels and the Russian mob, Philadelphia homicide detective Matt Payne struggles to dismantle an increasingly violent operation involving Russian sex slaves and kidnapped foster teens.