Athena, Maddie, Bobby, and the 118 race to save lives after a massive tsunami hits the Santa Monica Pier; Buck fears the worst when Christopher goes missing.
The 118 responds to a fire at a local animal shelter and races to evacuate all the animals. Meanwhile, Maddie takes a 9-1-1 call that sets her on a quest for answers.
When a murder weapon from a case close to Athena in the early '90s resurfaces, flashbacks to 1989 show how Athena joined the LAPD and became the police officer she is today.
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.
The 9-1-1 Call Center goes up in flames: Bobby risks his life to save 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.
Athena and the 118 race to save lives after a drunk driver causes a deadly pile-up on the freeway. Maddie goes into labor. Hen and Karen are devastated as they prepare for Nia to be reunited with her birth mother.
The first responders deal with a man trapped in a present, a mistletoe stunt gone awry and a Christmas-light showdown; Bobby contemplates his future with Athena.
Athena escorts a witness while handling a mid-air collision between planes caused by a bee swarm, showcasing her skills in managing crises and protecting lives.
The 118 responds to a call at a mega-church, where Bobby runs into his estranged mother. Meanwhile, Buck is looking to expand his social circle now that Eddie has left.
Emergencies include a skating mishap at an ice show, an accident involving a self-driving car and a fulfillment warehouse robot going rogue; Eddie's after-hours fight club gets out-of-control; Hen struggles in her relationship with Karen.
The 118 race to save the lives of workers trapped in a five-alarm factory fire. Maddie reveals a painful family secret that causes Buck to confront his childhood and answer why he is the daredevil he is today.
The members of the 118 make calls to save a bridezilla at a disastrous wedding and a mother trapped on her balcony. Hen plays medical detective when her mother falls ill. Athena uncovers a secret Bobby has been hiding.
