A full moon keeps the crew busy with some of the craziest calls yet, as Athena investigates a potential home invasion and "faces off" against a rabid criminal. Meanwhile, Abby helps investigate the murder of a caller, Bobby and Buck have their hands full at a yoga studio for pregnant women and Hen's past may become her future.

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.

Maddie goes for a ride-along with Athena in the hopes of being on the other end of a 9-1-1 call; Hen attempts to learn how to prevent her family from falling apart at the seams; disaster strikes at a military funeral and movie theater.

When the first responders race to the rescue of a crashed news copter, they unwittingly become the subject of an eager reporter's first on-air assignment. Meanwhile, Bobby tries to deal with his daughter's death, as Athena prepares for May's homecoming dance. Then, Maddie struggles to let go of her fear of the past. Also, the team responds to emergencies at an eating contest, a bodybuilding competition and a toddler pageant.

Bobby meets Athena's parents for the first time and Maddie attempts to end her marriage for good, causing Doug to insinuate himself even deeper into Chimney's life. Meanwhile, a tanker carrying a tiger shark crashes on the freeway and a gas leak in a plastic surgeon's office happens mid-surgery.

The First Responders rally together to search for a missing Maddie.

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.

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.

Athena and the 118 respond to bizarre emergency calls on Halloween, including a flock of crows terrorizing a field trip, an office employee having a close encounter with an eight-limbed creature and a ghost-like girl wandering a neighborhood.

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.

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.

The members of the 118 make calls to save a bridezilla at a disastrous wedding and to a mother trapped on her balcony. Meanwhile, Hen plays medical detective when her mother, Toni, falls ill. Also, Eddie and Christopher receive a visit from Carla, Athena uncovers a secret Bobby has been hiding that puts their marriage on the rocks and Maddie struggles with adjusting to motherhood.

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

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

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.

When a blimp suffers mechanical failure and its engine catches fire, Athena and the 118 must rescue victims both inside and outside a packed sports stadium. Bobby and Athena drop off May on her first day of college and discuss honeymoon plans, while Maddie and Chimney go to couple's therapy.

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.