"Fire" (Part 1) is the season premiere of the fourth season of the American police drama television series Homicide: Life on the Street. It originally aired on NBC on October 20, 1995. The episode was written by Julie Martin (from a story by Tom Fontana and Henry Bromell) and was directed by Tim Hunter. The two-part story centres on Pembleton and Bayliss' investigation into a pair of arson-related homicides, and introduces a new regular character, Arson Squad detective Mike Kellerman (played by Reed Diamond), who subsequently transfers to Homicide and partners with Det. Meldrick Lewis. This episode also flagged the permanent departure of regular characters Stanley Bolander (Ned Beatty) and Beau Felton (Daniel Baldwin).

As the episode opens, Kay Howard and Munch are on the station house rooftop, discussing recent events at a police convention in New York, where Bolander and Felton were among a group of 100 drunken police who ran amok at their hotel, and that this misconduct has earned them a 22-week suspension. As they talk, Howard notices a fire in the distance and they argue over its exact location. The action then cuts to the fire (in an abandoned box warehouse) where fire-fighters discover a charred body and summon the Homicide Squad. Pembleton and Bayliss arrive to investigate the death, and meet Arson Squad detective Mike Kellerman. He and Pembleton clash over Kellerman's assumptions about the victim's identity and manner of death. Believing the arson was for financial reasons, Kellerman meets an informant the next morning and pressures him to provide the name of the arsonist. Pembleton and Bayliss go to the pathologist for the post-mortem results, only to find that Kellerman has been there ahead of them. Hoping to link the dead boy to missing persons records, Pembleton visits Missing Persons, where he encounters his nemesis, Det. Roger Gaffney.

At the station house, Howard and Munch both declare that they will sit for the Sergeant's exam in hopes of gaining a promotion and the squad begins to stake odds on the outcome.

Capt. Russert and Col. Barnfather discuss the problems in the squad. Barnfather pressures Russert to improve the squad's cleanup rate, hinting that he might replace Giardello for being unable to control his detectives, and that he will hold Russert responsible for Giardello's "screw-ups". Kellerman visits the squad room to discuss the case with Bayliss and Pembleton, telling them he believes the building's owner, Matthew Rowland, is responsible for the recent fire, and for several other arson attacks on properties Rowland owns. While they are arguing, Lewis informs the detectives that uniformed officers guarding the crime scene have apprehended a teenage girl, Lisa Denardi, who was found poking around in the ruined building. When questioned, she reveals that she and her boyfriend regularly met there at night to have sex, and that they kept a sleeping bag there; from her evidence, the detectives conclude that the body is that of Lisa's 16-year-old boyfriend, Mark Landry. Kellerman visits a woman claiming to have information about the fire, but when he enters her house she strips naked and tries to seduce him so Kellerman hurriedly leaves.

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