As a geostorm ravages Earth, Athena and Hen's space mission teeters on the edge. On the ground, the 118 battles chaos when technology goes rogue.

As Athena and Hen navigate their way back home, Athena will be forced to confront what it means to live without Bobby.

Following the tragic events at the lab, the 118 must come together to lay their fallen hero to rest. Meanwhile, despite her own grief, Athena re-investigates the death of a child to help a grieving mother.

Athena and Buck are in a race against time to rescue the rest of the 118 following the fire in the bio lab.

The 118, still reeling from their recent loss, is dispatched to a mass casualty event after a high-rise apartment building collapses. Then, Athena and Chimney have to work together to save a familiar face.

The members of the 118 race to rescue a man who claims he was carjacked, shot and buried alive. Then, they arrive at a home where the owner thinks her roommate is a ghost, Hen receives a visit from the past, and Athena and family are concerned that Harry is still haunted by visions of Jeffrey.

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.

A man over-exerts himself exercising; a groundskeeper is cut by his chainsaw. An explosion occurs at a retirement community. May gets an emergency call from a suicidal teen.

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.

When Athena is assigned a rookie to mentor, she begins to question her own abilities. Meanwhile, Bobby and the 118 return to the set of "HOT SHOTS" following a 911 call.

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.

The 118 race to the rescue at a renaissance faire, then an office building when an overbearing boss is poisoned. Athena fears for May's life when she encounters a disturbed young man. Buck babysits Jee-Yun as Maddie and Chimney begin house-hunting. Eddie and Carla prepare Christopher for his first school dance.

Upon her return to shore, Athena's son, Harry, finds himself in trouble with the law. Meanwhile, Buck grows envious as Eddie forms a close bond with someone else, and the 118 rescue a woman who's stuck on receiving a rose at an iconic mansion.

Following the devastating fire at the Nash home, Bobby's fate remains uncertain, while Athena embarks on a mission to uncover the truth. Meanwhile, Hen and Karen engage in a heated custody battle, while Christopher grapples with forgiving Eddie.

Bobby and the 118 race to the rescue when an abandoned oil well erupts and causes a massive sinkhole in downtown LA. Athena investigates a 30-year-old cold case involving a casino robbery. Buck fears his relationship with Taylor might be ending, and Hen meets a man from her mother, Toni's, past.

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

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 118 race to the rescue at emergencies when a fire breaks out in an accountant's office and a car crashes into a "living funeral." Athena is shocked when a suspect dies in her custody minutes after she arrests him; Buck is attracted to a death doula; Maddie and Chimney panic when they are audited by the IRS.

Hen and Karen welcome a new addition to their family, while a call unfolds involving a person’s limb that’s taken on a mind of its own. Meanwhile, Eddie and Marisol take a closer look at their relationship, and Buck navigates his new feelings.

Maddie and Athena investigate a case surrounding an abducted mother and child as Hen and Karen learn more about Mara’s family history. Meanwhile, Eddie grapples with unresolved feelings for someone from his past.

The team races to save workers in a high-rise during a fire drill, car accident victims, and siblings fighting over a family heirloom. Buck gives Bobby surprising news. Eddie helps Christopher deal with the trauma caused by the tsunami.

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.

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.

Athena and the 118 race to the rescue when a fading movie star is plagued by a series of near-death experiences.

Things get messy for the 118 following a massive pipe explosion. Meanwhile, Athena investigates the brutal beating of a man found behind a grocery store, and Bobby's working relationship with Brad from "HOT SHOTS" just got a little more intimate.