On Sunday's episode of Chicago Justice, Nagel (Joelle Carter) and Dawson (Jon Seda) head to Chicago Med to interview the victim of an attempted murder: a man who was shot three times and left for dead, only to be discovered along with a kilo of heroin in his car that he swears isn't his. It appears to be one of a series of similar crimes, so Nagel and Dawson are hoping the survivor can provide them with the info they need to nail the perp.

And the case has a personal bent for Nagel, who has a connection to the victim dating back to their high school prom. Their history runs so deep that Stone (Philip Winchester) is initially hesitant to allow Nagel to work on the case, out of fear of a potential conflict of interest, but he eventually relents.

However, based on our exclusive sneak peek from the episode, he might not be making the right call — and Stone's not the only one who's raising an eyebrow at Nagel and the victim's relationship.

Chicago Justice airs Sundays at 9/8c on NBC.