A recovering Owen becomes the prime suspect in the serial arsonist case. Meanwhile, T.K. and Carlos find themselves in a fiery situation and Tommy gets the surprise of her life.

Owen helps Tommy through a personal emergency.

Captain Strand and the 126 come together when one of their own is trapped after a building explosion. Meanwhile, Owen reflects on his 9/11 experience, T.K. and Carlos come to a decision and Tommy and Julius decide on their future.

Grace is caught in the ice storm as she goes into labor, and Judd, Owen and Tommy race to find her.

As a wildfire spreads across Texas, Evan "Buck" Buckley, Henrietta "Hen" Wilson and Eddie Diaz from the 118 firehouse in Los Angeles arrive in Austin to help Capt. Strand and the 126. As the crews race to save a group of teenagers trapped by the fire at a campground, Owen and Hen fight for their lives in the aftermath of a helicopter crash.

Owen and the members of the 126 race into action when a massive dust storm engulfs Austin. Season finale

On her way back to Austin, Marjan is in for the fight of her life when she is targeted by a killer.

Grace and Judd fight for their lives in the aftermath of the horrific car accident, as flashbacks show how a childhood tragedy led Judd to meet Grace and how they ultimately fell in love.

Owen fears the past is back to haunt him when a stalker targets him and Catherine. Meanwhile, Tommy and Gillian face consequences when Gillian saves the life of a woman wearing a "Do Not Resuscitate" bracelet.

Owen is conflicted when his brother Robert asks him for help; Judd and Grace face a family crisis; As T.K. and Carlos prepare for their wedding day tragedy strikes.

Capt. Strand reveals to the 126 he has been working with the FBI to help bring down a domestic terrorist group with his Austin motorcycle club/gang The Honor Dogs, then race Owen to respond to a bomb threat at the State Capitol and put a stop to the terrorist deadly plans.

Owen travels to Los Angeles to confront his estranged father and some painful childhood memories. Wyatt acts out and prompting Judd to take him to his family ranch where an emergency brings them closer to together.

A bank robbery, an apartment fire and a pregnant woman lost in a parking garage are the seemingly unconnected calls to which the 126 responds. Then, T.K. celebrates his one-year anniversary of sobriety, while Owen and Gwyn may not make it to the end of the week as a couple. Also, Carlos finds himself working on a case with his Texas Ranger father.

Owen's first date with the beautiful and accomplished Chief of Staff to the governor of Texas goes awry. Meanwhile, the members of the 126 arrive at a house fire and find a couple's young daughter is missing. Then, Judd meets a teenager who has a profound impact on him.

Grace and Carlos work together when they suspect a young woman was a victim of a black market organ trafficking ring; Owen's brother Robert comes to visit and meet T.K., but surprises Owen with news that can affect the Strand family.

The 126 race to contain a toxic chlorine cloud of death unleashed by the train derailment. Owen names the station's new lieutenant as Judd finds a path forward.

Owen helps T.K. reconcile the past to help his future; Michelle learns the full truth about Iris.

Owen and the 126 race to the rescue when Catherine receives a package at the governor's office that may contain a bio-hazard. Meanwhile Grace and Carlos team up to investigate a prank 9-1-1 call that turns deadly.

Owen and the 126 deal with the aftermath of the asteroid crash in Austin while an even greater threat looms.

Owen helps defend Marjan when a rescue complaint forces her to make a challenging ethical decision. Meanwhile, Grace befriends a young boy who becomes a frequent 9-1-1 caller, but when she discovers he may be in some real danger she must step in.

When a dust-up between Owen and an obnoxious police sergeant goes viral, the existing tensions between police and fire rescue mount, leading Owen to decide they will settle the score on the softball field. Meanwhile, Grace competes against a hot shot call center night-shift operator when he moves over to the day shift.

Owen, Tommy & the 126 race to the rescue when a medieval-themed restaurant suffers a case of carbon monoxide poisoning. Meanwhile the crew is worried that Paul still has not mentally recovered from his surgery and his friendship with Marjan is over. Mateo is offered a promotion by his old fire captain, but quickly realizes he is not the man he once knew.

The 126 race to rescue a woman with an arrow shot into her head; Judd is doubly surprised by news Wyatt shares; Mateo helps a family member in need and comes to regret it.

The crew races to a disaster at a wave pool, and an outbreak of mercury poisoning that is leaving its victims in a a zombie-like state. Meanwhile, Owen must come to terms with his illness and what the side-effects of treatment may do to his vanity. Also, Michelle follows a new lead on her missing sister while TK is unsure how to handle his budding relationship with Carlos.

When she discovers her former fiancé is having a baby with his new wife, The 126 help Marjan enter the dating world through a series of chaperoned dates; Owen and the team are called to the rescue when a pregnant woman takes matters (and her anger) out at a motel where she suspects her husband is cheating on her.

Owen makes a decision about his future. Tommy receives devastating news. T.K. and Carlos worry about adopting Jonah. Mateo gets his immigration status threatened after an altercation. A doomsday prepper gets trapped in a bomb shelter and The 126 and all of Austin brace for an asteroid crash.

Judd calls out Owen's preferential treatment of T.K.. Marjan feels ostracized at her new mosque after another rescue video goes viral. Owen helps Michelle uncover new information about her sister's disappearance.

The 126 race into action when a horse barrels into a brewery with an unconscious rider on its back and then to a bus full of tourists all experiencing seizures. Judd introduces Owen to Wyatt's mother Marlene. Carlos and T.K. start couples counseling, when Carlos investigation into his father's murder becomes all-consuming.

The 126 race into action when an armored truck and its guards are attacked by a group of masked men. Carlos, in his new job as a Texas Ranger, is assigned to investigate the case. Owen attends group therapy with Tommy to deal with his brother Robert's death; Both Marjan and Paul each apply for the open lieutenant position, replacing Judd, who finds himself lost without his old job. Wyatt begins work at the call center and a major train derailment signals tragedy.

Judd literally walks into the line of fire when an armory catches on fire, sending bullets flying everywhere. Owen questions Judd's pledge of sobriety. Marjan introduces boyfriend Joe to her parents, Waleed and Nasreen, but their dinner doesn't go as smoothly as she hoped.

TK gets a huge surprise on his 30th birthday when his stepdad Enzo arrives in Austin along with TK's young half-brother Jonah; Owen's resentment of Enzo turns physical; Tommy is determined to push through her latest crisis; Wyatt attempts to talk-down a suicidal caller and the 126 must perform a dangerous surgery in the field after a man is impaled in a tree.

Facing his anger management issues, Owen has a breakthrough in therapy. Then, after a particularly devastating emergency call, Grace reaches out to a co-worker, but regrets when Judd offers more than she was planning. Also, a clown has an emergency at a young boy's birthday party, and Tommy, T.K. and Nancy race to help a survivalist who has a painful encounter with a reptile.

The 126 crew responds to a military tank on the loose in downtown Austin and a human pile-up at the roller derby. Meanwhile, new paramedic captain, Tommy Vega, joins the team and Owen is reunited with his ex-wife and T.K.'s mother, Gwyneth, and receives an update on his cancer.

Owen and T.K. risk their lives to save two brothers trapped in a homemade minefield. Meanwhile, Grace receives an emergency call from a conjoined twin who's brother is dying, Tommy interviews new candidates to fill the team's open EMT position and Paul's mother and estranged sister pay him an unexpected visit.

The 126 are called on the scene to a hoarder's rat-infested house, then are trapped in an elevator as a woman goes into labor. Tommy and Trevor host his ex-wife Cassandra for dinner which goes awry.

The crew race to a brawl at a male strip club, a fire at a bull semen factory and a protest where male toxicity is taken to a new level; Grace tries to reconnect with Judd; Owen faces the consequences of his chemo.

After being forced to take time off work to recover from his surgery, Owen finds himself immersed in the search for a serial arsonist. Meanwhile, T.K. and Carlos take their relationship to the next level and Marjan copes with the aftermath of losing someone on the job.

The 126 arrive at a funeral where another dead body has crashed the burial, and then to a hospital where an MRI has gone haywire. Owen and Tommy each feel displaced in their homes as Gwyn moves into the Strand household and Charles seemingly becomes the full-time parent in the Vegas'. Meanwhile, T.K. makes waves in his new position.

Owen Strand, the lone survivor of his Manhattan firehouse on 9/11, takes his progressive philosophies of life and firefighting down to Austin, Texas, where he helps the firefighters of Firehouse 126 start anew.

The 126 race to save a man crushed under a vending machine. While struggling to handle his aggressive foster horse, Owen finally faces the truth of his brother's death. As Mateo and Nancy scramble to delete a nude photo of her accidentally sent to the 126, Tommy is concerned that Nancy may be facing a possible health scare.

Owen and the 126 crew race to a gender reveal party gone horribly wrong, and a father/son trapped in a cave during a spelunking excursion. Meanwhile, Owen helps T.K. reconcile the past to help his future, Judd and Grace aid Judd's aging father.

Carlos is determined to solve his father's murder. Owen is offered a life-changing opportunity. Judd gives into his demons as Tommy begins her treatment.

The crew deal with a runaway bull at a used car lot and an apparent electrocution at the hands of an LA transplant; Michelle gets the strongest lead yet on her missing sister.

The crew race to a rattlesnake infestation, and attempt to rescue a man with dementia from a dangerous scene he created; Michelle learns the truth behind her sister's disappearance; A tragic accident shakes the crew to its core.