Homicide Sergeant Matthew Payne is used to murder, but lately there's been an awful lot of it in Philadelphia. A gangland shooting in a popular tourist location left six dead, most of them bystanders, and days later the headless body of a Latina turns up in the Schuylkill River. Everybody assumes that they're not related, but Payne can't shake the hunch that there's something more to it - and that hunch leads him to the Texas-Mexico border.