A serialized drama series based on journalist David Simon's nonfiction book about the Baltimore, Maryland, Police Department's Homicide Division. Follows the relationships that develop in the unit while the detectives go through their investigations. Detective Frank Pembleton is an intense loner and tough interrogator who is recovering from a recent stroke. His partner, Tim Bayliss, has been seasoned by investigations into some particularly brutal crimes. Mike Kellerman, the rookie, is a driven detective. Meldrick Lewis is a hard-working detective with a dry sense of humor. Even drier is Detective John Munch, the squad cynic. Guiding the team is Lt. Al Giardello, who continuously struggles with bureaucratic pressure while supporting his detectives and driving them on. Chief Medical Examiner Julianna Cox works closely with the detectives and isn't afraid to challenge their investigations.

This season introduces Detective Paul Falsone, a transfer from auto crimes, whose impulsive, intuitive approach to closing murder cases shakes things up; Detective Stuart Gharty, a veteran cop, who chose Homicide over retirement and is determined to prove himself to his new colleagues; and Detective Laura Ballard, a seasoned homicide detective from Seattle recently transplanted to Baltimore.