Denny Woods has found a witness in Olinsky's homicide case.
Ruben was a junkie that broke into Olinsky's car the night they were moving the body.
Voight tells Olinsky too stay far from away from Ruben as he investigates to see if they can find anything to make him unreliable.
Unfortunately, Voight realizes that Ruben has been getting his life together and even got back in his wife and daughter's good graces.
As Woods closes is, Olinsky is pushed to the edge and frames Ruben by planting drugs on him which ensures that his statement will be discredited in court.
The case-of-the-week finds Ruzek relying on his CI, Ray, who is also his former co-worker, to gain intel in a series of stash house shootings.
However, Ray has a bone to pick with Ruzek since he blames him for the situation that stripped him of being a cop.
Atwater ensures Ruzek that everything that happened was Ray's own fault, but Ruzek definitely carries some guilt.
When Intelligence realizes there's a leak, they turn to narcotics.
All of the evidence leads back to Rojas, however, she claims Ray, her CI has been playing her.
When Ruzek and Atwater try to find Ray, his girlfriend lets them know he made a run for it.
They finally find him hiding out in his boat and Ruzek realizes he still blames him for everything.
"All you had to do is testify," he tells Ruzek when he's backed into a corner.
He hopes that Ruzek will shoot him, arguably so he meets the same fate he did, but Ruzek knows better.
Atwater comes to his defense and they take Ray in.
Ruzek will live to see another day as a cop and his past will no longer haunt him.