As Joe Rorchek investigates a series of arson fires that occupy his firefighter sons, their unit also copes with the introduction of their first female crew member.
The battalion intends to give a boy a citation for his help with fires. But those plans are on hold when it's discovered the lad is the one who has been setting the blazes.
Joe gives away bride Constance to firefighter Charlie Bowers. The newlyweds' world is shattered when Charlie is fatally injured. Ted, the best man, takes Charlie's death very badly and freezes during a subsequent incident.
An arsonist is afraid that he can be fingered by a witness, but the woman he is tracking happens to be blind.
Danny learns that a young woman in his class is having dreams about some recent fires with details very accurate. The situation takes a twist when the visions start featuring Danny.
An imperious director wants Danny to star in his film, while ignoring a fire code inspection warning that his old studio lot is a firetrap.
A street vendor in illegal fireworks is causing destructive trouble in the neighborhood and a rift in the Rorchek household with his wares.
Danny finds out that his old gang is being framed for arson by their rivals. While trying to help Danny finds himself trapped in a blaze with members of the group responsible for the fires.
Task Force One finds itself in the middle of a potentially destructive family feud that mirrors some current friction between Ted and Chris.
A rural pipeline leaking toxic chemicals forces the evacuation of nearby buildings, including a barn where a young girl refuses to abandon a mare about to foal.
After a religious family's rented home burns down by accident, their adopted son convinces himself that it was arson and seeks revenge against the innocent landlord.
Danny's birthday party sparks reminiscences about the youth, seen in flashbacks, and occasions a showing of the department's history of fire disasters.
The Rorcheck family finds themselves at odds with fellow firefighters when they befriend a crippled former colleague. The problem is he blames Ted that injured him.
Overstressed by the job's pressures, Ted considers resigning while a line of cheap knock-off video game consoles is causing fires.
Danny fears losing his foster family when the firefighters undertake perilous rescue attempts during heavy rains.
A single oil field fire threatens to ignite the entire field. An egotistical expert is brought to help with the situation.
A pyromaniac arsonist is committing a series of firebombings with the crew of LAFD Station 1, especially Firefighter Haley Green, singled out in threatening letters.
A drug addict starts a fire in a hospital, jeopardizing an emergency operation involving Danny's friend, and a lab containing a deadly virus.
An old mining site that has filled up with toxic waste is hidden from view. When it suddenly collapses Joe, Haley and Danny are trapped and their lives in danger. The crew struggles to rescue them.
