Detectives investigate different homicide cases in inner-city Baltimore. Working for the police department, these detectives are committed to bringing justice to the streets of Baltimore.
Fire - Part 1: Pembleton and Bayliss investigate a body found at a burned building, joined by Kellerman from the arson squad. (S4, ep 1)
Fire - Part 2: Pembleton and Bayliss continue their investigation into the arson attack, narrowing their search down to a few surprising suspects. (S4, ep 2)
Newbie Kellerman is assigned to work with Lewis, as the pair begin an investigation into the death of an elderly lady waiting at a bus stop. (S4, ep 3)
Pembleton and Bayliss work with FBI agent Steven Van Brandt to stop a killer working his way up I-95 from Florida toward Baltimore. (S4, ep 4)
Pembleton and Bayliss investigate the murder of a man outside a gay night club. (S4, ep 5)
A Doll's Eye: Pembleton and Bayliss look for a gunman who opened fire at a crowded shopping mall, critically wounding a 10-year-old boy. (S4, ep 6) Also in UHD.
John Munch and Kay Howard try to frighten a drug dealer into confessing to murder, by using his love of Edgar Allan Poe's works to their advantage. (S4, ep 7) Also in UHD.
Sniper - Part 1: The detectives pursue a sniper who leaves games of Hangman at every crime scene. (S4, ep 8) Also in UHD.
Sniper - Part 2: Another sniper strikes Baltimore as soon as the first is apprehended. (S4, ep 9) Also in UHD.
Lewis and Kellerman take a road trip to extradite a Baltimore murder suspect from Pennsylvania. (S4, ep 10) Also in UHD.
During the investigation of a burglar found dead with no apparent injuries, the detectives find that he visited an ER for a gunshot wound. (S4, ep 11) Also in UHD.
Bayliss and Pembleton work with Lennie Briscoe and Rey Curtis to find the people involved in the NYC subway bombing. (S4, ep 12) Also in UHD.
Justice - Part 1: A murdered ex-cop's son decides to conduct his own investigation when Munch and Russert find themselves stumped in their search for the killer. (S4, ep 13) Also in UHD.
Justice - Part 2: The man who was acquitted of murdering a cop's father is found dead. (S4, ep 14) Also in UHD.
A male prostitute offers to reveal the identity of a multiple murderer as part of a plea bargain. (S4, ep 15) Also in UHD.
The murder of a young girl revives memories, especially in Bayliss, of an earlier case - Adena Watson, which was not resolved. (S4, ep 16) Also in UHD.
The desk clerk at the New Moon Motel hears shots and calls 911. Lewis and Kellerman find the body of an ex-con wearing only one boot. (S4, ep 17) Also in UHD.
Scene of a Crime: Two young black men are found shot to death at a project where Black Muslims have a security contract from HUD. (S4, ep 18) Also in UHD.
The body of a 71-year-old world class swimmer is found in a pool where the ME says he was for 24 to 36 hours. (S4, ep 19) Also in UHD.
Kellerman and Lewis dive into a drug war being fought through hijacked shipments, resulting in an innocent family being killed. (S4, ep 20) Also in UHD.
On his wedding day, Lewis is roped into the investigation behind a radio talk show host. (S4, ep 21) Also in UHD.
Three people are shot at a burger place, leading Pembleton and Bayliss to investigate. (S4, ep 22) Also in UHD.