The episode kicks off with a quick look at Upton's time in New York. She and Halstead have a quick "you miss me?" convo before he returns to work. 

Intelligence is debriefing about a white supremacist group selling uzi guns.

They believe a man named Tony Reed is at the head of the operation and hope to get to him using his right-hand man, J Hawk. 

Atwater's mission is to go undercover and snag a buy from J Haw, aka Jeffrey Hill, so that they can flip him on Reed. 

Atwater runs into some problems when he comes face-to-face with Tommy Doyle, the cop he previously had a racial run-in with while he was undercover. 

Doyle tells Atwater to get going. Shortly after, Voight realizes that Doyle was also undercover with Reed's crew for the past three months. 

Kenny suggests they all work together, but given Atwater and Doyle's history, Voight is skeptical. 

Kenny assures him that Doyle got a promotion to detective because he's a good cop and not because of the pl his family has in the police department. 

Voight agrees, and Doyle apologizes to Atwater and clears the air. 

They up the buy and Atwater secures it. J Hawk gets spooked by a helicopter and pulls a gun at Atwater. Doyle attempts to diffuse the situation by stepping in front of it. 

The cops bust in and arrest J Hawk. 

He refuses to turn on Reed, but Doyle is able to convince the boss to do the sale with Atwater anyway, and once money has been exchanged, the cops bust in and get him too. 

Everyone is impressed with Doyle and Atwater's work and Doyle suggests they celebrate with a beer. 

Atwater refuses, but Doyle insists since he saved his life. 

The two ride together, but when Doyle begins talking about the past, Atwater tells him to pull over. 

Doyle objects and states that they're in the middle of the Southside's war zone before noticing a black man walking with a duffel. 

Doyle immediately profiles the man as suspicious and believes he's going into a drug house. 

Atwater tries to calm Doyle down asking why he believes that, but it's clearly racially motivated. 

Doyle pulls the guy over and ambushes him. 

When the scared man begins to run, Doyle gets out of the car and runs inside the house after him. 

When Atwater hears multiple gunshots, he runs in and finds the man with the duffel dead. Two other people begin shooting at him, so he shoots back before administering aid to Doyle, who had also been shot. 

When Intelligence arrives on the scene, they find drugs, and Atwater doesn't say much about what transpired. 

He continues by going to a house to pay his respects for Doyle, who is being hailed a "hero."

From there, the search for the two "cop killers" continues until they pinpoint the owner of the getaway car, Jamal Pearson. 

Doyle's partner ambushes Pearson violently until he leads him to his basement where the two shooters are hiding out. 

They bring them in for questioning, but their stories add up -- they were sitting and playing Fortnite when their cousin, Sean Page, came by to drop off some shoes. A white man followed him and began calling them monkeys and waving his gun around. He then fired the first shot, which forced them to defend themselves. 

Voight doesn't believe a word, but Atwater begins to realize just how ugly this situation has gotten. He pulls Voight aside and tells him that Doyle had no probable cause to pull Page over and that everything he did was racially motivated. 

Voight informs him that they have a huge problem. 

Kenny arranges a meeting with Voight and informs him that he's heard rumors that Atwater wants to make this "racial" and tarnish Doyle's reputation. 

He tells Voight to stop it or else, which sounds like a thinly veiled threat, and Voight doesn't take well to threats. 

He informs Kenny that Atwater is like a son to him, but goes back and lays it all out for Atwater. 

He tells him he doesn't want to sway his opinion or change his mind, but he does want him to be aware of how much trouble telling the truth could cost him. Is it worth it?

Atwater struggles with the decision and turns to Ray Price, who is incarcerated. Ray bluntly tells him only a fool would take on the CPD and try to win and advises on keeping his mouth shut. 

However, he caveats by saying Atwater must do what he can live with. 

So, Atwater meets with his COPA rep and tells the whole truth. 

After, Voight and Ruzek toast to telling the truth and promises to have Atwater's back. 

Atwater goes home and sees Doyle's partner waiting outside of his house. 

He tries to get in his face when the whole block lights up in blue in solidarity with racist Doyle. 

Atwater stands proudly in the middle of the street owning his truth.