Intelligence is working a drug bust that goes sideways when Burgess notices the body of a woman lying in the bushes.
While making the discovery, Burgess cut her arm pretty badly and Voight told her to go to Med to get it cleaned up.
At the visit, the doctor informs Burgess that she's about 4-weeks pregnant.
Obviously, the baby is Ruzek's.
Burgess is shocked but goes about her day. When they're staking out a possibly suspect's place, Burgess informs him.
Ruzek is taken aback but promises to respect her decision.
The case goes from murder to kidnapping when it is revealed that the suspect kidnapped two women, one of which they found dead.
The search for the other woman leads them to the suspect's house.
Inside, they find Clarie, locked up in a basement clutching a teddy bear.
Claire is defensive but Burgess talks to her the whole time so she allows them to get close.
Claire begins to panic because Ray, the kidnapper, took her son Henry.
A search for Henry ensues and there's a time-crunch since he's diabetic and needs his insulin.
They trace the stolen vehicle that Ray is using to a local department store. Burgess spots Ray inside and attempts to lie low so he doesn't get spooked.
Chicago police pull up on the scene to get the stolen vehicle and Ray realizes they're onto him.
He begins shooting at the police. As they corner him, Burgess begs them to hold off on shooting him so they can get the location of the child.
One of the officers ignores her pleas when Ray points the gun at him and shoots.
Ray dies without telling them where he left Henry.
Another search party commences with Burgess and Ruzek eventually finding the young boy at a campsite.
He's unconscious but alive.
At the hospital, Claire thanks Burgess and tells her that despite having a baby with a monster like Ray, Henry is the best thing that ever happened to her.
This resonates with Burgess and she tells Ruzek that she canceled her appointment to get an abortion.
While she didn't expect to get pregnant now, she does want to be a mother and cannot let an opportunity like this pass by.
Ruzek supports her and tells her everything will be okay.