Morning coffee in bed is interrupted when Ruzek's sister fails to follow through on some family promise.
Irritated, Ruzek slams a nearby drawer forcing Upton to get dressed and warn him that she isn't into guys who have anger issues.
Ruzek promises it won't ever happen again and they head out to work.
She asks him to drop her off a little before the station so that no one figures out that something is going on between them.
However, they respond to a call of a woman screaming in a house nearby and almost ruin their cover.
Ruzek chases after the getaway car and almost gets run over as the driver reverses into him to get away.
Upton goes inside the house where she finds a woman badly beaten. As the woman takes her last breath, Upton is visibly shaken by the incident.
The woman is Alison Collier, the wife of a prominent Alderman, Jason.
When the rest of the team arrives on-site, Voight questions why Ruzek and Upton were together.
He tells Ruzek that if Upton's car "continues to be in the shop," he's going to have to report it to HR.
Ruzek nods but doesn't respond.
Intelligence grasps their first lead -- the shot-up car. They run the make and model through the system and narrow it down to Jerome who claims he had nothing to do with the incident.
His daughter comes outside sporting a black eye which forces Upton to go into "mama bear" mode and question the man.
Ruzek tells her he'll handle it as she begins to insinuate the man abuses his daughter without evidence.
Jerome admits that he lets his neighbor, Devin, borrow the car.
They arrive at Devin's house where initially, his grandmother refuses to allow them in claiming Devin would never be caught up in a murder investigation.
When she does finally let them inside, Devin makes a run for it.
At the precinct, Devin tells them he's innocent, providing the alibi that he was smoking weed in the park with God.
However, all the evidence, including the shot up car, and the witness testimony, point to him.
None of the detectives are able to "break him," not even Voight who tries to ruin his lunch.
Eventually, Upton decides to take a stab at it by exposing his vulnerabilities. She connects with him on his abusive past telling him personal stories of when her father beat her mother and siblings.
Devin finally confesses to the murder of Alison.
However, shortly after, forensics reveals the fingerprints on the crowbar belong to Nate, a kid who lives on the block with Devin.
They find threatening text messages from Nate on Devin's phone but when they ping the location, it leads them to a factory where Nate is also dead.
Upton goes to question Devin but sadly, she finds that he hung himself in his temporary holding cell.
"We're too late," Platt tells Upton as she cries over his dead body.
Upton takes the death hard as she feels like she provoked Devin. Halstead hangs out at her place to make sure she's okay, but when Ruzek comes to comfort her, he becomes suspicious of their "platonic" relationship.
The team tracks down surveillance footage and runs the plates their alleged suspect.
The results return the name Jason Collier, the Alderman.
Further investigation reveals that Jason was abusive and Alison wanted to file for divorce.
When Jason found out, he paid Nate to kill her while he was away on a business trip.
The team pursues Jason at his home. He makes a run for it and is eventually confronted by Upton.
He tries to provoke Upton to shoot him by moving in on her and even grabbing a gun and pointing it at her.
At the last minute, Ruzek comes to her defense and fires, shooting Jason in the back.
Voight questions why Upton didn't take the shots since she was clearly in danger, but Ruzek covers for her saying there were pedestrians nearby.
Later that evening, she admits the story about her father being an abuser was true and tells Ruzek she simply froze up.
The episode ends with Ruzek comforting Upton who has clearly had quite a day.