Lt. Casey butts heads with the new chief who fills in for Boden at House 51; Mullins has an unexpected surprise for Casey when he makes a risky move to stop a man from jumping off the building; Brett learns information about a friend.
While running a secret errand, Dawson finds herself trapped in a collapsed parking structure; pressure mounts on Casey as he begins taking on additional duties; Kidd grows increasingly skeptical of Hope.
Casey and Severide find themselves at odds after Casey argues with him over the best way to save a teenager entangled in barbed wire. When Casey looks to Boden for help smoothing out the situation, he comes to the realization that he will have to fix it himself. Elsewhere, Otis tries to convince Casey to participate in the beta test for an expensive piece of new firefighting equipment imported from Japan. Meanwhile, Kidd and Hope come to blows over a payroll issue and Brett goes on a date with a doctor she meets during an ambo call.
Kidd is surprised to discover she is being transferred out of the firehouse; Severide and Casey are suspicious and investigate; Otis and Herrmann discuss taking over a rundown bar; Dawson's frustration with her father reaches a boiling point.
Brett attempts to make a lifesaving decision in the field to someone near and dear to the firehouse family. In an effort to impress Lily, Otis scrambles to get everything together for the grand opening of Molly's North. Meanwhile, Boden becomes emotional following the rescue of a famous blues player from a burning apartment building and Dawson struggles to come to terms with how she has been dealing with her father.
After saving a young girl, Dawson is forced to make a tough decision when she finds out the girl's father is addicted to painkillers. Herrmann loses his cool and gets into an altercation with a police officer after responding to a call. Otis and Cruz are on a mission to find out who Brett is dating. Meanwhile, Boden is skeptical when Donna's brother Julian unexpectedly comes to town.
Dawson and Casey struggle to communicate; Brett and Kidd compete for the affections of a hazmat officer; Otis, Herrmann and Mouch search for the source of a stench that's making life difficult at Firehouse 51.
Dawson and Casey do everything they can to locate Bria's whereabouts after discovering important new information. Lt. Severide reunites with Chief Grissom, and old family friend. Meanwhile, Cruz enlists the help of Brett and Mouch to create a new tool and Kidd and Zach go on a date.
Casey and Severide disagree on the best course of action following a time-sensitive rescue; Herrmann tries to entertain his daughter on "bring your kid to work day"; Dawson joins Brett on a spa getaway; Kidd's social life gets a boost.
Boden has a lapse in judgment in the aftermath of rescuing a young boy. Kidd struggles to win the approval of Severide's mom after a surprise visit and Otis takes on new responsibilities at the firehouse.
Severide is surprised when Rene Royce returns to the firehouse; Casey helps Chief Boden in his latest pursuit; Kidd regrets a decision regarding Severide; Herrmann disagrees with Lt. Colan Nino over how to coach their son's basketball team.
Boden's chances for a promotion are met with potential complications, leading him to take matters into his own hands. Dawson and Casey don't see eye to eye on an important decision, while Kidd finds herself struggling to find time with Severide. Brett and Dawson respond to a tough call that quickly turns dangerous.