Mia Park

Lt Casey must work with Voight and the Intelligence Unit, Shay grows increasingly excited about the prospect of motherhood, and everyone comes together to support the opening of Molly's.

As the city is thrown into chaos by freezing temperatures, Sylvie gets trapped in a life or death situation. Plus, an abandoned baby is found at the Firehouse.

The Firehouse 51 crew have their work cut out for them when a tornado hits the city. Also, Brett must report Chilli after she makes a big mistake.

When Erin and Jay are called to a shooting at a family home, it appears the father's dark dealings with a dodgy pyramid scheme may be responsible for his loved ones' deaths.

Halstead and Manning deal with arguing brothers, one of whom needs a replacement kidney. One of Dr Reese's patients comes to a crossroad.

Doctors and nurses deal with a staff member's suicide; Choi and Halstead face off over how to treat a patient who is experiencing stroke symptoms; Manning treats a boy who fell into the river; Rhodes examines the man who saved Dr Manning's patient.