Athena investigates a mysterious murder 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 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.

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 Santa Ana winds bring in a variety of weirder-than-usual emergencies as the 118 respond to a family dog retrieving a severed hand and a young woman sleep-driving into the station. Bobby worries about his AA sponsor. Denny questions Hen and Karen about his biological parents. Chimney thinks he's found the perfect house for him and Maddie.

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.

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.

After the 118 responds to several calls from the same person, Hen steps in to offer them advice. Meanwhile, Eddie confronts his parents and takes a big step in his relationship with his son.