Casey's mom's parole officer stops by, and Casey is forced to lie to her after his mom reveals that she won't be able to pass the drug test. Meanwhile, at the station, Shay and Clarice meet with a lawyer to fight for full custody of Clarice's baby. The lawyer explains that Shay and Clarice need to move into their own place if they're going to have a chance at winning the custody battle.
The crew responds to a house fire and must scale the outside of the building to rescue residents on the top floor. Defying orders, Cruz enters the building to rescue a dog still trapped in the building. While he's inside, the roof collapses and Cruz must be rescued. Afterward, everyone is upset with Cruz for taking an unnecessary risk.
Back at the station, Chief Boden urges Casey to get Cruz under control. Meanwhile, Otis, Herrmann and Dawson discuss the business of fixing up their new bar. Otis says they could use Casey's contracting help, but unfortunately Dawson got on his bad side by fraternizing with Voight. Severide tells Shay that his ex-fiance, Renee, is in a psych ward. Shay decides to save the "we're moving out" conversation for later.
Casey has a conversation with Mouch, who is upset because he warned Casey about Cruz's erratic behavior. He says that if Casey doesn't solve the problem, he'll have to go straight to Chief Boden. Dawson and Shay take a homeless man to the hospital. While treating him in the ambulance, Shay accidentally sticks herself with a needle that she used on the homeless man. She'll have to wait for test results to find out if she contracted any diseases.
Dawson is upset that Casey won't talk to her, but Mills tells her to forget about it because she did the right thing, even if Casey can't see it. Shay finally breaks the news to Severide that she and Clarice have to move out. Severide says he supports her 100 percent. Cruz tries and fails to apologize to Mouch.
Casey scolds Cruz and urges him to turn in his badge. The next day, Shay and Clarice go apartment hunting and find a new home. Severide visits Renee in the psych ward, but she's clearly angry with Severide. Back at the bar, Herrmann, Otis and Dawson discover a safe inside the wall and debate whether or not to open it. Meanwhile, Casey meets with his sister to talk about keeping an eye on their mom while he's at work.
Later at the station, Severide tells Whaley about his visit with Renee. Whaley tells Severide he's glad the two are friends again. Cruz goes to church and struggles with the decision to retire from firefighting. After a vote, Dawson and Otis decide to open the safe, but they're interrupted by an emergency call.
A man has committed suicide and his apartment is wired with explosives. The firefighters decide to cut through the roof from the apartment upstairs. Inside, they discover an unconscious woman and Severide enters the wired apartment to save the woman. Luckily, the bomb expert defuses the explosive device and Severide gets the woman to safety.
Back at the station, Cruz relinquishes his badge to Casey. Mouch immediately feels guilty and asks Cruz what caused him to snap. Cruz breaks down and Mouch tells him that he's forgiven. It's a weight off Cruz's shoulders. Mouch stops Casey from reporting Cruz's resignation to Boden, and eventually Casey agrees to let Cruz stay on.
The next day, Shay receives a call from the hospital. The homeless man was clean, so Shay didn't contract any diseases. Meanwhile, Renee is released from the psych ward and Severide meets her outside and convinces her to talk to him. Otis, Dawson and Herrmann saw the safe open and discover a small wooden box inside. Casey's mom leaves to stay with a friend in order to relieve tension on Casey and his sister.
Shay is waiting to sign the lease on her new apartment with Clarice. Clarice arrives and tells Shay that her ex-husband agreed to split custody of the baby if Clarice moves to New York. She tells Shay that she took the deal, and she's leaving with the baby tonight. Shay is heartbroken. Meanwhile, Severide and Renee begin to heal old wounds, and Severide drops Renee off at her brother's house.