Costumed patients create a challenge for the doctors; Derek and Ben work on a new surgical technique; Richard asks a resident to perform his next surgery, angering Bailey.
Severide comes back to work, but isn't his usual self; Mills discovers more information about his father's family; Herrmann asks Molly investors to share ideas that could help turn the business around.
A couple they barely know invites Jules and Grayson to their wedding, but the date conflicts with Grayson's roller-hockey final. Tom uses eerily lifelike dolls to make a model of the neighbourhood.
After hearing Detective Gomez's wife's testimony at his malpractice trial, Elliot fears the worst. Plus, Rox tries to connect with Willis, but he pushes her away.
Ryan goes undercover in a white supremacist organisation to help stop the distribution of a deadly strain of tuberculosis. If he is unable to stop it in time, there will be deadly consequences.