Wozniak's suspicions land on Saperstein, forcing Harlee to convince Stahl to arrest Saperstein in order to keep him safe. Harlee visits her abusive ex, Miguel, who tasks her with tracking down the man who committed the murder for which he is imprisoned.
Harlee meets with her ex, Miguel Zepeda, in prison when he calls her. He wants Harlee to find Frank Kovach, the man he thinks really killed the runaway girl he was convicted of killing. Zepeda doesn’t know that Harlee set him up. He asks to speak with his daughter, Cristina.
Woz is upset that Harlee went to see Miguel and tells her to drop it. Then he tells Harlee that Saperstein is the rat. Harlee heads off to find Frank Kovach, despite Woz’s warning and takes Saperstein with her. Kovach punches Harlee in the face.
When Harlee fears that Woz is going to kill Saperstein, she has Stahl arrest Sapterstein to protect him. Before agreeing to testify against his friends, Saperstein says he has to talk to his mother. He tells her he has to go away on a case but she knows he’s lying. He also asks her about her blood sugar.
Saperstein then pretends his mother is having heart palpitations. He injects Stahl with something and then grabs his gun and escapes. Stahl puts out of Federal warrant for Saperstein’s arrest. Harlee tries to warn Saperstein not to go to Woz but he’s already headed to him.
Carlos, Loman, and Tufo head off find Frank Kovach’s girlfriend to track him down after he hit Harlee.
Harlee heads to Frank’s ex-wife’s house, Woz follows. They find her tied up and beaten. Frank made her call the school and give him permission to take their son. Loman, Carlos, and Tufo try to stop him but Frank hits Carlos with his car and injures his leg..
Tess confronts Joe, her husband about his cheating. He says he was just feeling old and it won’t happen again. The two have sex and she considers telling him she cheated too but she doesn’t.
Internal Affairs clears Loman of the shooting and releases his name to the papers. He goes to see Erica, the victim’s cousin whom he’s been dating at JJ’s baseball game but JJ already knows the truth. The boy screams at him, makes a scene, and Loman leaves, upset.
Cristina finds the letters Miguel has been writing her from prison. She decides to go see him in prison but the prison won’t let her in without parental consent. Harlee tells Cristina that Zepeda was her boyfriend at the time but he’s not Cristina’s father. She takes Cristina back home. Then she tells the prison that under no circumstances does Cristina Santos have permission to visit with Miguel Zepeda.
Harlee tells Cristina about how Zepeda made her feel special but she also shows her photos of when Zepeda beat her. Harlee says there was another man whom she loved but left when he found out she was pregnant. Harlee claims she told Zepeda but he refused to believe it. Cristina decides she doesn’t need to read any more of Zepeda’s letters.
Tess runs into Saperstein and tells him where to find Woz. Then she finds Harlee and tells her about the warrant. The two of them head to the construction site where Woz and Tufo are confronting Frank to get his son back. On the fourth floor of the construction site, Frank pulls a gun and refuses to turn over his son. Sap shows up and tackles Frank. Woz tells the son to watch and then sits back and watches the fight. When Saperstein knocks Frank out, Woz tells Sap he knows he’s the rat and pushes him off the fourth floor. When Frank gets up, Woz shoots him so that he falls over the half wall as well and throws the gun down after the two of them.
When Harlee arrives, Woz says that Saperstein shot Frank but Frank caused them both to fall. Harlee is horrified but then they hear Tufo call from down below that Saperstein is still breathing.