Ruzek visits his dad, Bob, and they plan his retirement party at a local bar.
When his dad doesn't seem to have the money, Ruzek jumps in with the cash.
On their way home from work, Ruzek decides to stop by Bob's and invites Burgess to tag along.
Inside, they find a crime scene and realize Bob has been kidnapped.
Voight explains that since this case involves a cop, they are going to keep it confidential.
Ruzek finds a cryptic text to his father's phone. He believes it's from a local bartender and confronts the man since his father had a gambling problem.
Benny informs Ruzek that his father paid off the $80k in debt about a month ago.
Ruzek then gets a video from his father who informs him that a local gang wants information on a snitch. If he can get them the name, they'll set him free.
Intelligence begins investigating the gang, and Burgess discovers that Ruzek's father already tried to find the name but didn't have the proper security clearance.
Ruzek gets another video from his dad that if they don't get him the name soon, the gang will kill him.
Ruzek wants to trade "Merlin" for his father, but Voight informs him that they won't be trading in one life for another.
He contacts a task force, who reveals the name of the gang leader instead.
They look into Lucas Barela and pinpoint a warehouse where they successfully find Bob.
At the hospital, Ruzek confronts Bob who begs him to let the case go and let Barela walk. Otherwise, Barela has the power to take him down and destroy his legacy.
Ruzek is upset. He confides in Voight, who informs him that they will be pursuing Barela and urges Ruzek to stop covering for his father.
They find Barela's hideout, and Voight tells Ruzek to wait until everyone arrives.
Ruzek goes inside anyway, while Burgess remains on watch. She hears gunshots, and when she runs to the backyard, she sees Barela dead with two shots to the back.
She asks Ruzek what he did, but he informs her the shots were clean.
He recounts his story to Voight.
Burgess confronts Ruzek and continues to question the shoot.
Camera footage from a nearby building reveals that Ruzek's shot was a good shot. Barela reached for his gun, which is when Ruzek shot.
Ruzek goes to his father's retirement party briefly before going back home to drink in the dark.
Burgess comes to his apartment to clear the air, but he informs her that she questioned his character today.
He reveals that he would've never done that to her because he knows her heart and he thought she knew his too.
Burgess apologizes, but Ruzek shuts the door in her face.