Last week’s epic “Chicago P.D.” episode saw Sergeant Hank Voight (Jason Beghe) being investigated by a committee after a string of complaints were filed against him. Things got worse when Voight realized that a wrong man was convicted in a case seventeen years ago. Fortunately, in Season 4, episode 20, the Intelligence Unit worked card to overturn a wrongful conviction and free an innocent man from jail.

What will happen this week in NBC’s “Chicago P.D.”?

Well, things are going to get really interesting in the Windy City. According to the official synopsis of Season 4, episode 21, Voight’s team of detectives will investigate a string of armed robberies. In “Fagin,” the team is called to investigate a robbery that is currently in progress at a bank. However, the investigation gets complicated when Detective Hailey Upton (Tracy Spiridakos) arrives at the crime scene and tries to take over the investigation.

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Upton is from the robbery-homicide unit and seeing that a robbery is in progress with the potential to turn violent, she wants her team to head the investigation. In fact, she and Voight butts heads very often in this episode. It will certainly be nice to see a hard-nosed woman battle Voight. And Upton isn’t afraid to call a spade a spade.

Unfortunately, the robberies are not restricted to just one bank. Multiple thefts take place in different parts of Chicago. Detective Erin Lindsay (Sophia Bush) will be forced to make a decision in the heat of the moment which reveals a surprising suspect behind the mask.

In fact, the promo of the upcoming episode hints that the person behind the robberies is someone known to Voight’s team. In the video, the robberies are revealed to be violent in nature. Voight agrees with Upton that these people need to be put down as soon as possible. During a chase, Lindsay catches one of the robbers and unmasks them and it seems like she knows who it is.

Spiridakos, who plays the new robbery-homicide detective, is a temporary replacement for Detective Kim Burgess (Marina Squerciati). Squerciati’s real-life pregnancy meant that “Chicago P.D.” writers had to write her character off for some time. Hence, Detective Upton takes Burgess’ place in the upcoming Season 4 episodes.

Fortunately, the replacement is only temporary. Squerciati will be back to the police procedural in Season 5. In the show, her character has taken a leave of absence so that she can take care of her sister and her niece, the former was brutally assaulted during a night out.

Interestingly, Detective Upton has a special connection to Desk Sergeant Platt (Amy Morton). What exactly this connection is will be known during the episode.

Furthermore, only three episodes are left for “Chicago P.D.” to wrap up its fourth season. The Season 4 finale premieres on Wednesday, May 17 at 10 p.m. EDT on NBC.

Catch new episodes of “Chicago P.D.” on Wednesdays at 10 p.m. EDT on NBC.