Harlee and Wozniak lead the crew on a dangerous mission to steal Bianchi's secret ledger and take down the mobster once and for all. But the plan takes a tragic turn, forcing Harlee to turn to an unlikely source for help.
Harlee and Wozniak break into Bianchi’s attorney’s office and steal his secret box, but it’s got a special lock they can’t open. On the way out they are spotted by an intern. When Woz wants to killer, Harlee decides to let her go, but girl later tells her boss about the man and woman who broke in.
Harlee and Wozniak set up Bianchi for his girlfriend and his hitman’s murder. They have Nava get a search warrant for Bianchi’s home and plant blood evidence. Verco intercedes just as they pick up Bianchi and he is turned over to the Organized Crime unit.
Stahl is upset when the hair he took from Cristina’s brush isn’t viable for a conclusive DNA test. He edits together recordings of Miguel from his prison phone calls, in order to lure Cristina out of school to meet him.
Harlee gets a phone call saying that she needs to make sure Bianchi is released or else Cristina will be killed. They have Cristina’s phone and they’ve turned off the GPS. They send Harlee a video to prove Cristina is safe but that someone is following her. In the video, Woz spots Stahl in the background. Harlee calls Stahl and explains that Bianchi’s men are stalking Cristina. He tells her they are at Union Square.
Harlee and the team arrive but can’t get near Cristina without the shooter getting to her first. Harlee calls Stahl back and convinces him to get Cristina to the subway while they take the shooter down. Stahl also grabs Cristina’s coffee cup to get her DNA. The shooter takes a hostage, and Woz shoots and kills him.
Later, Harlee visits Stahl to tell him never to go near her daughter again. Stahl says he’s lost everything, which makes him free. He tells Haree that her secrets have poisoned her but that’s okay, because soon he’s going to heal her.
Woz finally manages to break into Bianchi’s lock box. He finds recordings, DVDs, and photos of Julia and Gail Baker.
The image gallery for The Quality of Mercy may be viewed here.