On one of the hottest days of the year, the first responders feel the pressure as harrowing incidents keep happening around the city, including a road rage accident involving a van full of tourists, an emergency at an auto-repair shop and a grenade. Meanwhile, Buck gets a surprise visit from his sister, and a handsome new hire Eddie jeopardizes Buck's chances of being chosen for a fireman calendar.

When a massive earthquake rocks Los Angeles, the first responders rush to rescue victims from a crumbling high-rise hotel both under the rubble and high above the ground. Athena must deal with wreckage from a collapsed freeway overpass and Maddie is thrown into the fire as she faces her first crisis as a 911 dispatcher.

When Metro LA's 9-1-1 system is hit with a massive system-wide power outage, the call center must go old school in responding to emergencies. The first responders must deal with explosions in multiple homes and a difficult child birth. Meanwhile, Michael confronts Bobby about parenting his kids.

The 118 deals with a situation where a stunt driver is placed in a precarious position, two mail bombs are detonated and a teenaged social influencer loses their mind; Eddie's family decides to visit; Buck confronts a deadly series of events.

A massive tsunami hits the Santa Monica Pier, placing Buck and Christopher's lives in danger .

Athena, Maddie, Bobby and the 118 races to save lives after a massive tsunami hits the Santa Monica Pier and Buck fears the worst when Christopher goes missing.

Accidents happen at a bowling alley and a home renovation; Athena pursues a car thief.

Maddie fears for herself and her co-workers when the call center is taken hostage.

The Hollywood Reservoir dam breaks. The team adjusts to life during the pandemic.

The 118 believes their fabled firehouse superstition has come true when they have the day from hell with a never-ending series of bizarre emergency calls - Athena is in hot pursuit of a 118 firetruck; a man who duct-taped himself to freeway billboard, a garage full of fireworks and a restaurant manager destroying his own business. Meanwhile, Eddie feels a spark with Christopher's former teacher, but admits to Bobby he may not be ready to move on in his personal life just yet.

Athena and the 118 race to save lives after a drunk driver causes a deadly pile-up on the freeway. Meanwhile, Maddie goes into labor and Hen and Karen are devastated as they prepare their foster daughter, Nia, to be reunited with her birth mother.

The 118 responds to a series of calls dealing with parents and their children, including a disastrous birthday party thrown by a mommy blogger. Meanwhile, Athena and Michael talk to May about her past suicide attempt, Chimney and Maddie adjust to life with their newborn, and Hen and Karen are emotionally shattered as their foster daughter, Nia, is reunited with her birth mother.

The members of the 118 rush to the site of a hit-and-run that leaves a familiar face in critical condition. Meanwhile, with Buck's help, Athena investigates the case of a missing woman last seen in a casino and Josh recalls an emergency in 2006 that led him to become a 9-1-1 operator.

When a famous mystery writer dies, Athena, Bobby and the 118 respond to the chaos caused by a city-wide manhunt for buried treasure the author left behind.

In the aftermath of the shooting, Athena and the 118 are on high alert when a sniper is targeting members of the LAFD. Meanwhile, Maddie makes a life decision. Season finale

A series of ransomware threats leads to an overabundance of emergencies for the 118, including a medevac helicopter crash at a hospital and an air-traffic control tower system failure. Meanwhile Athena must revisit her traumatic attack when the case of the realtor serial rapist goes to trial, Eddie suffers a health scare and Maddie's postpartum depression worsens.

The 118 springs into action when a city-wide blackout and a record heatwave causes mayhem in Los Angeles. Meanwhile, Chimney confides in Hen about Maddie's condition, and Athena's worst nightmare comes true.

As the citywide blackout continues to cause mayhem in Los Angeles, Athena races to save her family from a tragedy. Meanwhile, Eddie must make a difficult choice about his future, and Maddie makes a life-changing decision.

The members of the 118 arrive on the scene after a truck crashes into a high school homecoming parade. Meanwhile, Athena and Michael try to help Harry in the aftermath of his kidnapping, May is intimidated by returning call center legend, and Bobby gives a devastated Chimney advice regarding Maddie.

Bobby and the 118 race to save lives after an explosion rocks the hospital where Dr. David Hale is performing surgery. Meanwhile, Michael makes a life changing decision.

The members of the 118 are called to series of emergencies around Christmas Eve. Then, Eddie struggles with an emotional Christopher.

Athena, Bobby and the 118 "speed" to the rescue to save a family whose pick-up truck has been rigged with a pipe bomb which will detonate if the vehicle slows under 55 miles an hour. Meanwhile, Eddie has a rough transition into his new job, Buck makes an impulsive relationship decision and Hen is reluctant to accept her new partner in Chimney's absence.

Athena investigates a robbery at a gas station that takes an unexpected turn when the would-be victim turns the tables on her assailant. Meanwhile, Bobby and the 126 race to rescue a novice diver who panics while in a shark cage, and a house sitter terrified of spiders. Then, Eddie reaches his breaking point, Chimney returns to the 118 and Maddie shares some news with Buck, who realizes he has to come clean with Taylor.

The members of the 118 race to the rescue of a social media influencer when she has an accident in a sauna, then to an emergency at a reality show wedding, and finally a tragedy when a mother and her daughter go hiking. Meanwhile, Maddie worries she has missed too many firsts with Jee-Yun, May questions Athena's career path, and Hen and Karen attempt to recapture the fun.

The 118 races to the rescue when the 9-1-1 Call Center goes up in flames. Then, Bobby risks his life to save a trapped May, and Claudette, Buck and Eddie work together to help an injured electrician, and Chimney and his brother team up as firefighters for the first time.

Another day in the life of the 118, as its members race to rescue a cliffside wellness retreat guru after his followers turn on him. Then, they respond to an emergency call at an upscale hair salon. Meanwhile, Maddie contemplates returning to work, Eddie and May make decisions on their future, as do Buck and Taylor, and the 118 gathers for a surprise wedding.

Athena investigates when the same house is hit with two home invasion 9-1-1 calls within hours of each other. The 118 race to the rescue when a D-I-Y home renovation traps a man in an attic. Hen asks for a second chance with her medical school professor. Maddie and Chimney regret hiring a nanny for Jee-Yun after the woman completely takes over their apartment.

The Santa Ana winds bring in a variety of weirder-than-usual emergencies as the 118 respond to a family dog retrieving a severed hand and a young woman sleep-driving into the station. Bobby worries about his AA sponsor. Denny questions Hen and Karen about his biological parents. Chimney thinks he's found the perfect house for him and Maddie.

The 118 race to rescue two roommates desperately trying to find a needle in a haystack at a landfill, and help a woman whose nightmare dream suddenly becomes a painful reality. Athena and Maddie team-up to find a missing boy in a crowded mall; Chimney debates if the time is right to propose to Maddie.