It's Take Your Father to Work Day on Thursday's episode of Chicago Med-- but not in a good way.

In our exclusive clip, Dr. Halstead (Nick Gehlfuss) brings his father Pat (guest star Louis Herthum) to the ER, where the elder Halstead promptly waves off a wheelchair, after refusing to be brought to Gaffney in an ambulance.

Will and Dr. Rhodes (Colin Donnell) team up to figure out exactly what's wrong with Halstead's father, and determine that his heart is essentially working overtime to compensate for a faulty valve. "First time I've ever heard of hard work being a bad thing," Mr. Halstead says gruffly.

Rather than being proud of his son's medical capabilities or grateful for the help that's being provided to him, Pat curtly dismisses any concerns about his condition. The sneak peek provides a clear picture of why Will's brother Jay (Chicago P.D.'s Jesse Lee Soffer, who also guest-stars in the episode) refused to speak to their father for so many years.

Chicago Med airs Thursdays at 9/8c on NBC.