Voight is still reeling from Noah's death and laser-focused on the whiteboard of evidence that they have for the open investigation.

Voight fixates on Jo Petrovich's profile on the killer. He keeps hoping to find something new. They don't have any new leads on the case. Hailey checks in with Voight and offers to stay and go over everything again. He checks in with her as well to ensure that she's doing okay. She tells him that he doesn't have to worry about her.

Hailey has a sleepless night and goes through her new routine. She goes for a run when. We see a sequence of her running every day and trying to beat a certain time.

She gets an alert about an abducted kid, a nine-month-old baby, and she responds to the call.

While responding to the call, Hailey happens across the baby's father, assaulting someone at gunpoint who he feels has taken his baby. Hailey has to talk the man down.

Voight arrives to the scene, and they go over all the possibly entry points. They find broken glass in a garage window and the alarm supossedly went off, but the parents say they didn't hear it.

The father seems a bit shifty.

They notice more blood drops in the room and a bunch of things (Clothes, diapers, etc) missing. It's clear the abductor knew the code.

Hailey brings Jo Petrovich into the fold becaues of the nature of the case. The person of interest was an unhoused  man who doesn't seem good for it.

The blood belonged to Baker, and Hailey and Jo (who isn't used to being in the field at all) head to find him.

Hailey sees the car, it's empty, but he sees a car seat in there. They notice Baker, but the baby isn't with him. He gets spooked when he sees a police car in the vicinity and takes off running. Jo and Hailey go after him, and Baker starts shooting and shoots a civilian. Hailey tends to the civilian and Jo goes after Baker but does little to stop him.

Hailey looks over the footage and studies Jo. She realizes that Jo lied about not having a clean shoot because of a pedestrian, and she asks Voight about cases.

He says that Jo has the highest case closings but doesn't put her name on things because she doesn't want to go to court and she is great at reading people

Hailey and Jo talk to the parents again to see if they know anything about Baker. Jo notices how violatie the father is and wants handwriting samples from both of them. She tells them she needs handwriting samples.

Jo's hand was shaking at the scnee. She thanks Hailey for backing herand takes a moment in her car. Hailey studies her. It appears as though Jo may be drinking.

Hailey eyes Jo's backpack, wondering what was in there while they go over things in the bullpen. When Jo walks away, Hailey looks in Jo's bag and smells presumably alcohol in her canteen.

While driving to Baker's place, Hailey confronts Jo about her drinking and expresses she knows the signs from growing up with an alcoholic.

They get a lead on where Baker is and go to his house but he's dead, he's been brutally stabbed, and the baby isn't there.

Tammy, Baker's girlfriend, has Grace according to the neighbors.

Jo concludes that Tammy wanted the baby; she didn't want to ransom. They find a picture of Tammy with Grace's father. He admits that he had an affair with Tammy.

Grace's mom says it wasn't the first affair, and she knew. It's been a constant thing and he's still having affairs and that's why they weren't home when Grace was taken. Trent, the father, was out with a woman, and Grace went to confront him and left Grace alone.

They walked home, and neither of them checked on the baby when they got home. Trent admitted that Tammy didn't like how things had ended. She got pregnant and had an abortion and she knew the code to the house.

Tammy always wanted to go to Mexico, where her family is, so they have to look into places where she'd try to get there.

Hailey and Jo get a lead on where Tammy could be, but Hailey ensures that Jo hasn't had anything to drink in a while and she's sober befeore they head to the station.

Hailey spots Tammy at the station with a baby and her hand in the diaper bag with a gun in it. She tries to talk things through with  Tammy.

Tammy blames the father for making her get rid of her b aby and learning she couldn't have any more chidlren. Things escalate and Tammy pulls her gun out and is about to shoot Hailey when Jo shoots her in the head.

Hailey sends Jo to the hospital to get checked out and covers for her.

Jo meets up to thank Hailey when they're running. Hailey tries to advise her about her drinking, but Jo calls her out on punishing herself with her running as well.