In Tucson, a young man is found shot to death on the street. Detectives Bill Hanson and Mike Carroll follow two clues that could lead to a suspect -- a dropped cell phone and a pawnshop slip tucked in the victim's pocket. In Memphis, Sergeant Debo Carson investigates the brutal murder of a woman whose body was found dumped on the railroad tracks. The case takes a dramatic turn when a tip comes in about a man who may know details about the murder that were never released to the media.