When a routine security run goes bad, how far will Halstead go to get justice for his friend?

"Chicago P.D" has shown time and again that the world of law enforcement is difficult and dangerous. While you're tasked to uphold the law, there are instances when you can't get justice.

That certainly was the case in the show's heartbreaking 16th episode. In "The Cases that Need to be Solved," the detectives of the "Chicago P.D." scrambled to make sense of a case where a 6-year-old African-American boy was shot execution style. While they were able to find the culprits of the heinous crime in the end, it's unclear what kind of justice will be given to the victim as he was killed by two young boys, a 10 and a 12-year-old.

The team will be faced with another challenging case that might cause one of them to cross the line. A synopsis posted on Carter Matt for episode 17 reveals that Halstead (Jesse Lee Soffer) and several of his colleagues were attacked while working on a routine bank run for a dispensary. The incident happened while the detective was on his off-duty security gig. Voight (Jason Beghe) and Lindsay (Sophia Bush) soon discover that the dispensary owner had received several threats from local gangs. Meanwhile, Halstead and his colleagues Antonio (Jon Seda), Atwater (LaRoyce Hawkins), Burgess (Marina Squerciati), Roman (Brian Geraghty) and Ruzek (Patrick Flueger) track down a suspect.

A trailer for the upcoming episode, "Forty-Caliber Bread Crumb," hints that Halstead is really shaken up about the incident. Viewers are given a glimpse of what went down as the clip shows money being counted by machine and a woman confirms to Halstead and his colleague that the money amounts to $200,000. As the money is being transferred, Halstead looks worried and says that something doesn't feel right. Sure enough, a burning car seems to have been dropped in front of their vehicle and his friend is shot.

In the aftermath, Halstead is seen breaking down in tears and lashing out, as he throws someone against the wall. It comes as no surprise that Voight appears to empathize with Halstead as he gives him 5 minutes with the suspect. The clip ends with Halstead entering the holding cell, looking angry and determined.

While it's easy to see why Halstead wants to exact his own brand of justice, he is an officer of the law. And hopefully, he remembers that.

Episode 17 of "Chicago P.D." season 3 will be aired on March 2.