Intelligence is celebrating at Community Play on Chicago PD Season 5 Episode 6 when they are forced to put the champagne down and respond to shots fired.
Once on the scene, they find several family members shot to death.
The son somehow survives and is able to ID the shooter, Quinton Kane, who his father was moving massive amounts of cocaine with.
Intelligence tries to come for Kane but after the son passes away, they have no witnesses.
Their focus shifts to the death of McGrady, a narcotic sergeant who was running an open investigation into Kane.
Upton is visibly shaken by the death of her old colleague, especially when she's blamed for his death because he went in solo while they were supposed to be working the shift together.
The blood on the gun that killed McGrady matches Kane's so they put out an arrest warrant for him.
Except Kane is working with the Reverand, who convinces Voight to peacefully bring him in and hear his side of the story.
Voight agrees, even though "peacefully" means that Kane is pointing a gun at him the whole time.
After McGrady's wife tells Upton about the Community Play treasurer accusing him of stealing money, she realizes something isn't adding up.
She figures out that McGrady stole a vial of Kane's blood to frame him for his suicide.
Voight encourages Upton not to tell anyone the truth about McGrady and to let him die a hero.
If they were to disclose this information, McGrady's children wouldn't get their father's healthy pension.
And Kane, who was guilty of murder, would walk free because of the lack of evidence.
So while unethical, they both agree to take McGrady's secret to the grave.
Ruzek kept getting calls from Mia, which Atwater thought was some "one night stand," but it turns out, it's actually his sister.
Denny Woods reveals that he knows all about his sister's DUI and the fact that he falsified documents to cover it up.
He's so desperate to get any incriminating intel on Voight, he blackmails Ruzek into being the mole.
In exchange, he'll keep both of them out of prison.