Things have been hot and heavy between Ruzek (Patrick John Flueger) and Upton (Tracy Spiridakos) on Chicago P.D., but their secret fling just hit a small snag. In this exclusive sneak peek of Wednesday's episode, titled "Tue or False," Ruzek earns the first strike in their relationship when his heated reaction to a family issue rubs Upton the wrong way.

In the video, Ruzek angrily slams his fist on a side table and goes on a mini-tirade when his sister calls to tell him she can't drive their father to a doctor's appointment. Upton flinches at the startling gesture before telling him, "Yeah. I get it. But I don't do yelling and I don't do slamming. Not even a little bit." Given her visceral reaction, this probably isn't the first time she's seen a man angrily slam his fist.

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Still, Ruzek manages to smooth things over with a frank apology and Upton makes it clear he's been warned. In the meantime, they'll try to keep their relationship a secret, which will be easier said than done since they work with the city's best detectives who are experts at piecing together small clues to form a full picture. That means they'll have to take extra precautions, like not arriving to work at the same time as Upton suggests, if they want to continue keeping their relationship on the down low.

Secret fling aside, Upton will also be forced to dig deep emotionally when she reveals a dark secret from her past in order to elicit a confession. Plus, Voight (Jason Beghe) finds himself under pressure from Brennan (Anne Heche) to close a case when an alderman's wife is beaten to death.

Watch the drama unfold when Chicago P.D. airs Wednesday at 10/9c on NBC.

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Tracy Spiridakos, <em>Chicago P.D.</em>Tracy Spiridakos, Chicago P.D.