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 leaves two dead and many others injured; a motel room blows up, killing two and severely injuring two more; and the body of a headless Latina turns up in the Schuylkill River. Everybody assumes the deaths are not related, but Payne can't shake the hunch that there's something more to it -- and that hunch leads his thoughts far from the City of Brotherly Love, to the Texas--Mexico border, in the person of a long, lean Texas Ranger who's come to Philadelphia tracking a particularly nasty murderer with Mexican cartel connections. With the body count rising, the odd couple of the Philadelphia cop and the Texas lawman race to find the gang and make them pay for it.