When a man who is part of a crew preparing a house for demolition returns to get something he left behind, he sees a light and approaches the door when it opens suddenly and he is knocked down and he sees someone wearing an S & M mask. When the one in the mask leaves he goes into the room and sees another person also wearing a mask dead. SVU is called in to investigate. When they take off the mask they see that the person is a teenager.They find instruments that appear to be used in underground fighting. Warner says he bled to death, he was probably struck by one of the instruments and a major artery was struck.
Outside there's a crowd, Fin talks to one of them who tells them that there's a convicted sex offender living in the neighborhood. Fin and Munch go to the apartment and find that someone sprayed "rapist" on the door. The landlord tells them where he works. Stabler and Benson go to speak to him and he denies their allegations. They go to the woman who spray painted his door who tells them that her son is missing and suspects that he had something to do with it. They take her to identify the body and she says it's her son. Cragen was about to send someone to arrest the guy when a young man comes in saying he has video of the boy who was killed. Cragen, Stabler, and Benson watch the tape while Munch and Fin interview the boy, Scott Heston. Cragen and Stabler deduce that they were staging a fight so that they could put it on the internet but things went out of control when the boy who was killed, Riley was struck in his vital artery. Stabler goes into the interview room and listens as Scott says that the other guy was someone he never knew who knew Riley. But Stabler tells him that when Riley was fighting the other guy the camera was still which meant no one was holding it. So that means Scott was the other guy.
Scott is brought to trial and the defense tries to put on a defense claiming that Scott was acting out over his depression. After the trial while the jury is deliberating, a girl, Cassandra Sullivan approaches Casey telling her that she is Riley's girlfriend and that Scott had some kind of obsession for her. The jury comes back and finds him guilty of negligent homicide. After the verdict is read, Scott stares at Cassandra which Casey notices. Later she goes to her home and asks her to tell her what happened between Scott and Riley. She tells her that she and Scott had sex once and Scott was hounding her. Casey asks her to speak at Scott's sentencing.
Stabler and Benson go to see Scott about what Cassandra said about which he denies.
At his hearing Cassandra doesn't show and Casey is worried. Later they learn she was hit by a car. Stabler goes to the Transportation office to find out what happened and they find a photo of Cassandra being hit. The driver in the car Stabler recognizes as a friend of Scott's. Stabler interrogates him and he admits Scott paid him to hit her.
Benson goes to see Cassandra in the hospital, the doctor tells her that while she was treating Cassandra she discovers that can't be a teenager, that she has to be in her late 20's.
They check her out and find out that she has been pulling some kind of scam wherein she claims to be a teenager to get into foster care. When Stabler and Benson confront her about it she denies it.
Later Scott's lawyer shows up at SVU insisting that Cassandra or whatever her name is to charged with raping Scott. Stabler thinks this is just a ploy for his defense of Scott at his trial for what he did to her.
Stabler and Benson tell Casey they learned that 12 years ago she was placed in foster care after being abused by her parents. And apparently liked it that she didn't want to give it up. Casey has her thrown out of foster care and arrested for fraud. She goes to see Cassandra and offers her a deal which would get her probation but she refuses.
At her trial, after Scott testifies, she examines him and attacks him which leads to the judge declaring a mistrial.
Later Casey brings one of the her foster parents to her who shows her photos of her when she stayed with them. She acts ungrateful to the woman. Later Stabler and Benson enter and Casey tells them she'll refile and hopefully she'll accept her offer. But they say that she might have to face other charges in other cities. When news of her came out some of her other victims have come forward while the statute of limitations has run on some of them there are still some that she can be prosecuted for. When they show her the photos of her victims. She claims she loved them all. But they ask her why she left them. She answers cause they got older and she didn't.