The unit is out celebrating Trudy Platt's 25th year on the job when Voight gets a call from his C.I about a drug mule.
When the squad arrives at the run-down motel, they corner a man who makes a break for it and opens fire.
Inside, they find a woman in the bathtub with her stomach slit open.
The Jane Doe and the suspect link back to the Scorpion club, an establishment that was in the gutter just a few weeks ago before suddenly coming into a huge sum of money.
Upton goes undercover as Riley, a flirty party girl looking to score some blow from the bartender, Larry.
Larry is more than willing to trade his pure blow for something sexual, however, Upton halts his advances by telling him she has a rich boyfriend who would like to make a deal.
The following day, Larry introduces Riley's rich guy, Ruzek looking dapper as Jake, to the club owner, Spiro.
Spiro expresses interest in selling to Jake and things seem to be going well until Ruzek's father, Bob, walks in as Spiro's security detail.
Ruzek is unsure of what it all means so he asks Upton not to report it for now. He know there's no way his father is dirty and confirms it the next day.
Bob tells Ruzek he's just making a few extra bucks.
The unit tries to use Spiro's girlfriend Rita against him, but unfortunately, they find her dead the next morning in her apartment.
Ruzek tries desperately to secure a buy so they could take down Spiro.
When he finally does, his father shows up as the driver.
Ruzek is upset because he told his father to "get out" of the business. Voight is afraid Bob will ruin the deal, however, Ruzek assures him again that his father isn't dirty.
During the deal, Bob stumbles into the warehouse pretending to be looking for the bathroom.
Spiro tries to keep the situation calm, however, Morales senses Ruzek's uncertainty and points a gun at him.
Bob panics, and in an effort to protect his son, starts shooting.
He gets hit by a bullet which "passed through him."
At the hospital, he tells Ruzek that he knew something shady was going on but needed the money because he's broke and a few days away from losing the mortgage.
Visibly worried, Ruzek asks why he didn't ask for help, but Bob tells him that a father never asks his son for money.
Upton comes to the hospital to check up on Ruzek.
Back at the station, Voight assures Ruzek that his father is "family" and he took care of it by backtracking the books so it reads as if Bob was undercover for them.
Ruzek is beyond grateful.