In September 2020, LA is rolling back COVID restriction when a microquake triggers a dam break.
Earlier that day, Athena starts back at the office for the first time in six months, while May shadows Maddie at the call center.
When the dam breaks, a city bus is hit by debris and thrown into an office building several floors up. As Buck attempts to secure the bus to get the passengers onboard off safely, the 118 realizes a man is trapped underneath the bus.
Once the passengers are safely out, Bobby stays on board with the last teenager as the bus rocks back and forth and the man trapped underneath is saved. A small explosion rocks the bus, but Bobby is able to shield himself and the teen.
A biker is trapped in a drainpipe after being hit by the dam water. Flashbacks show her life throughout quarantine, including the death of her husband due to the virus. While on the phone with Maddie, she locates a box that she breaks into and releases the spillway. Firefighters then rescue her.
Athena gets on the ground and goes around to residential neighborhoods making sure people are evacuating. She gets to the house of a mysterious woman who informs her she hasn’t left her home in seven years. Before they can get out the front door, the house collapses, and the Hollywood sign starts to crumble under the force of another earthquake.