A young boy is found on an amusement park ride, beaten to death. Surveillance camera footage shows the young boy getting out of a cab at the amusement park. Stabler questions the driver. The driver sees a photo of the boy and says it's his nephew, Ethan. The boy's mother comes in to identify the body. When Ethan's mother finds out he was beaten to death, she tells SVU that the school bully Blake did it.
Blake tells Stabler and Fin that Ethan's Uncle Joe was teaching him how to fight. Joe spent time in prison for fraud and is now $147,000 in debt. Fin and Stabler want to interview Joe. They spot him in the woods with a group of teenaged boys. Some of the boys fistfight while others cheer them on. The fighters tell Stabler that they're in a club. The members compete, beating each other up. Fin and Stabler bring the guys in for questioning.
Ethan's Uncle Joe is brought in for questioning, as is the kid accused of fighting with Ethan before his death, Nicky. Nicky's stepfather Hank is also brought in, since he was cheering the fight in the park as well. Nicky's mom Sandra shows up to take her son and husband home. Meanwhile, Joe is devastated that his betting cost Ethan his life.
It pains Stabler that the DA can't find any charges that can stick. Now he has to watch Hank, Nicky and Deborah walk out of the squad room. Cragen warns Stabler that despite his suspicion that Hank is beating up both Sandra and Nicky, he needs to let the case go. Stabler breaks his promise and visits Nicky the next morning at school, finding him bruised and scared.
Stabler takes Nicky and heads to his house to confront Hank. There, he finds Sandra with another cop. She fingers Stabler as the man who attacked Hank. Back at the squad room, Hank and Sandra are interviewed about what happened while Stabler is interrogated for the assault on Hank. An altercation breaks out. Nicky tells the cops that Hank beats him and his mother and Sandra beat up Hank the night before to frame Stabler for assault. Fin arrests Hank on the spot.
Nicky tells Stabler about how his stepfather would enter him in fights and gamble on him. If Nicky didn't win the fight he'd get a beating at home, too. Nicky gets emotional when Stabler asks him what happened to Ethan. Nicky admits that despite the unfair size difference, he fought Ethan in a match. With Hank's encouragement, Nicky kept hitting Ethan until he was unconscious and later dead.
The next morning at arraignment Hank gets bail until his hearing. The judge orders him to stay away from Sandra and Nicky in the meantime. Stabler isn't so sure that Hank will abide by the rules. Cragen and Stabler head to Sandra's house later that night to check on Nicky. They hear a gunshot. Inside, they find a bruised and battered Sandra, Hank dead from a gunshot wound, and Nicky huddled in the corner with the gun.
The ambulance takes Sandra to the hospital. Her main concern is her unborn baby. Nicky tells Stabler he's happy he shot Hank in the head. Stabler shakes Nicky and tells him to not confess to anything without a lawyer present. Nicky is taken to the precinct.
The crime scene investigator tells Stabler that the crime scene tells a different story than what Nicky said. The bullet hole shows that Nicky shot Hank execution style while he was kneeling down, and not in the heat of the moment when Hank was attacking Sandra.
Stabler and ADA Hardwick interview Sandra in the hospital room. She admits she never saw Nicky shoot Hank, but knows he did it to protect her. Hardwick tells Sandra that they have enough evidence to prove Nicky lied about what happened. Outside Sandra's room, Stabler lashes out at Hardwick for wanting to press murder charges against Nicky.
At SVU, Hardwick reads Nicky his rights and tells him she's charging him with second-degree murder. Defense attorney Debbie Marsh walks in and announces she's representing Nicky for free. Debbie is sure she'll get a not guilty verdict. The next day at the hearing Stabler is called to the stand. Hardwick asks what Nicky told him right after the cops arrived on the scene. Stabler is forced to say that Nicky admitted he's happy Hank's dead and he's happy he put the gun to his head.
Outside the courthouse, Stabler finds Sandra and tells her she's the next witness to be called. Sandra's scared to face a jury and admit she witnessed Hank beating Nicky, but Stabler reminds her that this is the least she can do for Nicky to make things right. Later on the stand, Sandra drops a bombshell and admits she shot Hank, not Nicky. Evidence suggests that either Nicky or Sandra could have been the shooter.
Because evidence clearly indicates that both Nicky and Sandra were lying about what really happened on the night of Hank's murder, Hardwick and Stabler want answers. Stabler tells Nicky and Sandra that he won't press charges against either of them, but they need to come clean about what happened. Both mother and son stick to their stories, so Stabler tells them they're free to go. Stabler tells Hardwick that it doesn't matter - they'll never know who the shooter is.