It takes a team of people to help answer the famous question, "911, what's your emergency?" Detective Athena Grant works as a member of the police force, handling cases that require her sharp mind and expertise, while also trying to juggle her own family drama. Bobby Nash and his team of firefighters help execute the daring rescues that often come along with these life-threatening situations. Meanwhile, Abby Clark spends her days taking and fielding emergency calls at the 911 call center, but constantly desires to know what happens after she sends help.

In the aftermath of a deadly plane crash, Bobby and team race to help the survivors, while Athena deals with panic and chaos at the airport. Bobby confronts his past demons; Athena is out for revenge against a group of teen bullies; and Abby delivers an important message from a 9-1-1 caller.

On Valentine's Day, a surprise marriage proposal goes awry with dangerous consequences. Athena attempts to help a desperate woman and unintentionally joins the Lonely Hearts Club. Bobby and Chimney pull holiday duty and learn about the "Casanova Fracture" and Abby and Buck go on their first official date.

The first responders take calls to help an unusual domestic disturbance, a "death" at a psychic's and a horrific motorcycle crash. Meanwhile, Bobby dips his toe into the dating pool, Abby takes a walk down memory lane, Buck is confronted by his past actions and Athena tries to start her new life.

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.

The first responders continue to deal with the fallout of a massive earthquake and its deadly aftershocks. Athena tries to keep the peace as Bobby and team continue to rescue victims from a collapsing high-rise hotel, both under the rubble and high above the ground. Maddie 's first day on the job involves helping a pregnant couple deliver their baby safely.

The holidays are naughty and nice for the first responders, who must deal with a stampede at a toy store, a mistletoe stunt gone awry and neighbors competing in a Christmas-light showdown. Meanwhile, Bobby contemplates his future with Athena, Chimney and Buck attempt to lift Maddie's spirits and Eddie must decide if he wants to give his son what he really wants for Christmas - a visit with his mom.

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 first responders deal with a calamity at a chocolate factory; a mail bomb explosion; Eddie receives some surprising news from Shannon; Maddie contemplates her future in the call center.

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 .

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.

A dry thunderstorm rolls over LA, bringing in a series of lightning strike emergencies for the 118 and leaves a first responder's life hanging in the balance. Athena and May go undercover at the rehab facility to help Bobby with his investigation into his sponsor's mysterious death. Maddie dreads her parents visit to her and Chimney's new and unfinished house, while Chimney get a surprise of his own from a visiting Albert.

A series of freeway car accidents leads to a catastrophic overpass collapse that endangers the lives of civilians and members of the 118.