Teresa Colvin's father owned a store and went broke paying off precinct captains, building inspectors, and thugs. It broke his heart and wrecked his marriage. Thirty years later, she's finally able do something about it, because she's now the city's first female superintendent, in charge of a 10,000-member police force.
Colvin asks Alderman Ronin Gibbons to fund a task force on city corruption. Noting that he helped get her the job, he denies the request. He doesn't think she's capable of taking him on, so she'll form an unofficial task force.
Detective Jarek Wysocki and his partner pull alongside a speeding stolen car. Jarek recognizes the driver, and promises he can say good-bye to his pregnant girlfriend if he drops the gun. When he does, Jarek keeps his word, then arrests Luis, and demands a new partner.
Meanwhile, Gibbons meets Fergus Construction comptroller Linda Walling, who's learned that the firm's bidding on city contracts is rigged and will cost Chicago millions. She knows Gibbons is on the firm's board. Whom should she tell? Him, he says.
Colvin finds Jarek - they were former partners - examining the body of a gang member that the Black Lords dragged from a funeral home, shot again for effect, and left in the street. He was the cousin of incarcerated rival Latin gang leader Paco Fierro, who's furious. Colvin will talk to Paco. She also wants Jarek on her task force, telling him and his new partner, Caleb Evers, to check out a double homicide in Grant Park.
It's Linda Sullivan and her husband, who were shot while jogging. When Evers notices an iPod was stolen - an unlikely crime for the location - Colvin tells Jarek to check out the Fergus offices.
Colvin tells Paco the police will raid the Black Lords, so chill out. He gives her until his midnight release date.
Jarek's niece, Vonda Wysocki - her father was also an officer, who was killed in the line of duty - and her partner, Isaac Joiner, are at one of the raids when they spot a felon with an outstanding warrant. They chase the man into an abandoned house. He surprises and decks Vonda, but a trailing Joiner takes him down.
In the Fergus lobby, Jarek tells Evans when he hears the word "institution" to go pull the building's fire alarm. Looking over the employees, Jarek notes one man's face and says the magic word. As they exit, Jarek slips him a phone number. He calls Jarek and says Linda learned the bidding was bogus and talked to someone at City Hall about it.
Meanwhile, Colin can't fire an officer with 12 citizen's complaints on his record, so she demotes him. "You can't change the way things get done in Chicago," he roars, threatening her.
Jarek and Evans tell Colvin they know where to find the suspected killer, Wendell Holmes. Colvin tells Jarek that she has an undercover cop drawing connections between Gibbons and the Irish mob.
Before meeting Colvin and Jarek, Gibbons recites a list of "favors" he's performed for a host of Irish names. She gives Gibbons their lead, Jarek mentions Fergus, and Gibbons promises help.
Jarek spots Vonda and Joiner at the Holmes stakeout, gives them a list of Holmes' felonious friends, and tells them to bust one. Jarek also suspects that Vonda is sleeping with Joiner.
Meanwhile, Jarek's ex-wife, Dina, calls, asking about his fiancÃ©e, adding their son, Josh, left his homework at Jarek's, so can he bring it by? Then Holmes takes off and gets caught with the iPod in his pocket. Seconds later, two Irish thugs arrive. One is mouthy Will. The other's undercover Liam, who Jarek punches, and sends away.
Once Holmes learns that his buddy has been busted with stolen merchandise and told police that Holmes had asked him to lose the murder weapon, Holmes admits he was paid to make it look like a robbery - and the woman was the main target.
Jarek meets with Liam, who says he heard "Jasper" hired the shooter. Jarek tells Colvin to say the shooter is named Jasper so that Liam's cover isn't blown. Then they tell Gibbons what they know, adding that they want to search Fergus.
They arrive at the Fergus offices, and find Liam and Will trying to sneak out. (Evans notices something fishy about Liam.) Gibbons and owner Owen McDonnell show up, say that Jasper is a pipe vendor from Boston, who's at the airport. Jarek gets the flight stopped, citing "terrorist intent."
Under interrogation, Jasper admits that Gibbons and McDonnell wanted Linda gone, but they didn't directly order a hit. Colvin and Jarek are frustrated. Jarek quits her task force, dumps his partner Evans, and heads to his ex-wife's, with whom he has sex, hiding in a closet when their son suddenly arrives home.
Meanwhile, Colvin's driver, officer Antonio, persuades the Black Lords to give up the grave-robbing shooters in return for the raids to stop. Antonio returns to the car amid gunfire. He takes shots meant for Colvin, who gets hit, then the shooter escapes.
As Gibbons watches news of Colvin's shooting, he orders a drink - and his secretary to kiss his ear. Meanwhile, Evans tells Jarek that Colvin was wearing a bulletproof vest, so she'll be OK. But Antonio is dead.
Jarek asks Evan if he was lucky to spot an undercover Liam. Evans says no, he's just really good. Jarek wants him back as his partner. They find Colvin in tears, saying that Antonio made her wear the vest because of the fired cop's threats. Jarek rejoins her task force, adding that Chicago is a city that "knows how to punch back."