When the Hollywood Reservoir dam breaks, Bobby and the 118 race into action to save passengers on a city bus that has crashed into a building several stories in the air. Maddie must first locate, and then rescue, a trapped cyclist, and Athena helps an agoraphobic woman evacuate her home. Meanwhile, the team adjusts to life as first responders during the pandemic. Bobby worries if Athena is ready for field duty since recovering from her physical and psychological injuries; Chimney takes extreme precautions around a pregnant Maddie; and May begins a surprising new job.

In the aftermath of the dam break, massive mudslides wreak havoc throughout Los Angeles. As Athena fights to save herself and an agoraphobic woman after her house collapses, Bobby, Hen and Eddie rush to save hikers endangered by the falling of the Hollywood sign. Meanwhile, Buck and Chimney must rescue a group of pregnant women trapped in a submerged house.

The 118 race to save a man under siege by his high-tech smart home, and a yoga teacher who has lost her vision. Athena hunts down a bank robber disguised by Covid protocols. Meanwhile, Buck confides in Maddie, Hen clashes with her antagonizing medical school lab partner and members of the 118's crew prep for an out-of-state mission.

Athena investigates a mysterious cuddle during a neighborhood block party and the 118 rush to save lives endangered by a bomb threat. Meanwhile, Chimney has a hard time keeping secrets when Maddie and Buck's parents come to town.

The 118 race to save the lives of workers trapped in a five-alarm factory fire. Meanwhile, Maddie reveals a painful family secret that causes Buck to confront his childhood and answer why he is the daredevil he is today.

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.

The 118 rush to save a man pinned under a Humvee, and a garage band that rocks out too hard. Enlisting Bobby and Athena's help, Michael installs a new "rear window", and turns into an amateur detective after noticing strange behavior at a nearby apartment. Meanwhile, Hen's mother unexpectedly arrives and announces she is moving to LA, and Buck's re-entry into the dating pool ends in disaster.

The 118 are called to the tarmac when a flight attendant reaches her limit with her flight's passengers. Athena discovers that quarantine has pushed a couple to their breaking point. Meanwhile, Eddie worries Christopher will not accept him dating, Buck reconnects with an old flame and finds himself in the middle of Albert's new relationship and Maddie and Chimney make a big decision about their baby.

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 sleeping 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.

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.