After picking up a present for Matt for his promotion ceremony, Gabby notices that a construction crew is causing damage to a parking structure. She races in to evacuate people, but ends up getting caught in the collapse with no way to contact the rescuers outside. The foreman that chased her inside dies when his skull is crushed. Other victims find their way to Gabby: an army sergeant, a bank teller suffering from anxiety, a racist woman, and a social worker are the first ones found. The woman is confrontational with basically everybody except the sergeant. The sergeant starts out seeming like he'll concede to Gabby's expertise in matters, but quickly takes over, mansplaining and he-peating his way to the role of "leader." They find a man trapped in his car, but the sergeant doesn't want to listen to Gabby when she stops him from just wrenching the car apart. The car is holding up one of two support poles, and if anything is moved to quickly the ceiling could collapse. After the man is rescued, the sergeant ignores her advice that they shore up the support poles and instead convinces everyone to try and dig out, even after Gabby points out that doing so could destabilize matters further. As the man from the car recovers, the social worker figures out that his daughter is stuck in the elevator. They manage to get her out, and as the building settles more it becomes obvious that Gabby was right. They change course to shore up the post. The bank teller passes out, and Gabby realizes that they're all suffering from carbon monoxide poisoning. The sergeant volunteers to go and shut off the car that was trapped while it was running, even after Gabby explains that it's probably a one way trip. The man from the car is an electrician and he's able to get the emergency phone from the elevator working again. After speaking to Casey, Gabby gets everybody to the evacuation point only to turn back at the last minute to go after the sergeant. Casey ends up going in after her, and all three emerge with only minor injuries.
As Casey gets ready for his promotion ceremony, more and more work is piled on him. Severide seems to be mildly jealous of the attention, but every time he sees Casey with more work, he's reminded that he's happy where he is.
Brett asks Hope about the stolen money, but Hope explains it away as small town gossip stemming from a dalliance with her old boss. Kidd tries to keep an open mind about Hope, but when Hope gives a flimsy excuse about why she didn't complete a task, Kidd sees right through her.