On one of the hottest days of the year, the first responders must deal with harrowing incidents all around the city; Buck gets a surprise visit from his sister; Athena questions her relationship with Bobby; Buck worries about a handsome new hire.
A massive earthquake rocks Los Angeles; the first responders rush to rescue victims from a crumbling high-rise hotel; Athena must deal with wreckage from a collapsed freeway overpass; Maddie faces her first crisis as a 911 dispatcher.
The first responders continue to deal with the fallout of a massive earthquake; Athena tries to keep the peace as Bobby and team continue to rescue victims from a collapsing high-rise hotel; Maddie must help a pregnant couple deliver their baby.
The first responders race to rescue victims trapped in various tight spots; Athena contemplates accepting a promotion that will take her out of the field; Chimney finally deals with the aftermath of his near fatal car crash.
Maddie goes on a ride-along with Athena; Hen must figure out how to save her family from permanently falling apart; the first responders deal with emergencies both at a military funeral and a movie theater.
The first responders unwittingly become the subject of an eager reporter's first on-air assignment; Athena prepares for May's homecoming dance; the team responds to emergencies at an eating contest, a bodybuilding competition and a toddler pageant.
Halloween finds the first responders racing to the rescue at a cemetery, a haunted hayride and a spooky parade; Maddie thinks she has received a "ghost" call from a missing hiker; Hen is in a life-or-death situation with her father.
Buck jumps back into the dating scene but fears he will return to his old ways; a woman goes to great extremes on a freeway overpass to get the attention of her husband; a couple have a car accident on their wedding day.
Hen relives her evolution into the firefighter she is today as she recalls the first times she met Chimney and Athena.
During the holidays, the first responders must deal with a stampede at a toy store, a mistletoe stunt gone awry and neighbors competing in a Christmas light showdown; Bobby contemplates his future with Athena; Chimney and Buck try to help Maddie.
Bobby meets Athena's parents for the first time; Maddie attempts to end her marriage for good, causing Doug to insinuate himself even deeper into Chimney's life.
Looking back at how Chimney joined Station 118 and became the firefighter and paramedic he is today.
The first responders rally together to search for a missing Maddie.
The call center is hit with a system-wide power outage and must go old school to respond to emergencies; the first responders must deal with explosions in multiple homes and a difficult child birth; Michael confronts Bobby about parenting his kids.
When a going-away party for a bank manager turns into an emergency, the first responders are accused of pulling off a daring heist.
After his devastating family tragedy in Minnesota, Bobby Nash moves to Los Angeles to start over, where he becomes captain of the 118 and meets Athena Grant for the first time.
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.