Olivia plays with Noah in the park. A lady asks how old he is and tells her to enjoy it. She now has a fourteen year old with big problems.

Mr. and Mr. Evans (parents of missing girl) are panicking because they can't get ahold of their daughter. No one has seen her.

Lady is still talking to Olivia and Olivia realizes Noah is missing.

Mrs. Evans says Lily's friend Peter hasn't heard from her. Her iPad is password protected, surprising her parents.

Olivia finds Noah.

Mike doesn't think this is an SVU case. The cops discover Lily's iPad contains photos and messages from an older guy named Diego who her mother has never heard of and is sure her daughter doesn't know.

Benson comes in and wants info. Mike says it's not a missing kid, it's a 15 year old who ran away with an older guy. He's very cynical about the whole thing.

Lily's friend Peter comes. He is just a friend but is very worried about her. He says she's been weird lately. Cutting class, leaving at lunchtime, smelled like cigarettes or maybe pot.

Mrs. Evans says Lily is not like that, is not moody like other teens, etc. Peter says Lily says she can't talk to her parents. She has some new friends and wants to hang out with the cool girls. They went to some frat parties in Tompkins Square.

Fin busts Diego who insists he kicked Lily out when he found out she was only 15. He is arrested for child porn for the photo of her on his phone.

Sonny doesn't think Diego did it.

Dodds says Dodds Sr says teens don't get taken, they run away. Benson doesn't agree.

Lily's bag is found under the West Side Highway. Her parents want to know where their daughter is. Benson tries to keep them calm as Mrs. Evans wants to run to the crime scene to try to find her daughter.

Sonny sees sneakers sticking out of a blanket. He asks Mike for permission to open it. They find Lily. She's dead. Dodds is upset thought he says he's okay.

Mrs. Evans asks if they're sure. Benson is sorry for their loss. She asks if they are up to making a preliminary ID. They show her photo on a tablet and Mr. Evans ID's the body. Mr. Evans thinks it was the homeless guy who had her atm card. Mrs. Evans wants to see her.

Warner says she died from a blow to the head and slow bleed. No evidence of sexual assault but there was semen on her thigh. Warner meets Mike. He asks what to tell the parents.He realizes that when talking to them the day before Lily was probably still alive.

Homeless guy says he was in St. Lukes ER during murder. Someone stole his cans so he was happy to find the card. Sonny is able to confirm it.

Warner comes in. There was a partial overlap in DNA in the semen. She's guessing the perp was half brother to the DNA they have in CODIS.

Dodds interviews the half brother, Brendan Cohill. He is in the system because he jumped a turnstile. He doesn't know any half brother. He is adopted and doesn't know his birth family. He has his mother's name and address but never contracted her.

Cops interview the birth mother. She doesn't want to tell who the father was. She was 16 and the guy was married. Benson says the wife doesn't have to know. Anyway the guy died give years ago. His name was Ray Marino. He had two sons, George and Robbie. She has the home numberbut please don't tell about the affair. She asks what her son is like and Benson says he has a successful life.

One of the Mr. Marinos wants to know why his DNA is needed. He sas he didn't kill her.

Robbie Marino seems like a Fonzie wanna be. Sonny says he has the kind of blanket Lily was found in and that he was arrested 2 years ago for aggravated sexual assault.  His brother is questioned by Dodds who accuses him of covering for Robbie. George says Robbie's had a hard time and always does things the sutpid way. He confesses Robbie gets high and forgets where he's been, so he told him he advised him to always use him as an alibi. Fin asks if Robbie is capable of murder. George hopes not.

Dodds tries to make Robbie look at the photos of the dead girl. He keeps saying he can't look. Fin says CSU are still looking at his van and the moving blankets. Benson tells Fin to call Warner.

Robbie wants to sleep but Sonny says tell the truth. Mike says to tell them she got into the van. 

Benson calls Mike out. Warner says DNA doesn't match any of these people. Possibly another brother. She needs Ray Marino's DNA but he's been dead five years. Benson says they can exhume the body.

Fin takes photos of the exhumation for Rollins.

Warner says he must have had a son with a third woman based on DNA. She thinks the killer is younger than the other three boys.

Mrs. Marino is upset and doesn't want to cooperate. They have to break the news that her husband had another son. She says that's not possible. They were together for 40 years, since 8th grade. She wants to sue the NYPD for messing with her family. George tells her not to let her blood pressure go up.

Out of Mrs. Marino's sight, George admits his father was a player. There was always a woman behind him when he drove his city bus. He remembers when he was 12, his father took him and Robbie to a Labor Day carnival and met this woman who had five year old twins. He was jealous because his father won a foam football George wanted and gave it to the other boy. After he made George and Robbie promise not to tell that they met Stella, who worked in the museum.

Stella says that the male twin died in a motorcycle accident 10 years ago. Is he being blamed for an accident? She is confused about what's going on. She says he cheated on her with her best friend Helen. 

Helen says her kids come home every Sunday afternoon. Sonny asks if she and Ray were more than acquaintances. She wants to know what's going on. She denies the affair but says her husband won't be happy if she or her kids talk about Ray. Mike thinks they should get a warrant for the DNA of every male of the correct age on City Island. Then he wants to arrest the guys and make up an excuse later. Benson tells him no.

They set up a checkpoint to stop one of the Ryan boys and check out his car. Dodds saw ratchet ties in his van so held him for longer. They got DNA off the breathalyzer. It matches the DNA found on Lily. 

Sonny talks to Gary's dispatcher to find out where he's at now. He tries to run away from the cops who give chase and Dodds is rough with him as he catches him. Some guy is videotaping as the guy shouts he is being hurt.

Fin says they don't need Gary's statement but Dodds wants to know why. He wants to get a confession and promises not to coerce it. He feels responsible because he didn't believe Lily was kidnapped. Benson says he can't blame himself. She agrees to come with him to a confession.

Gary had seen Lily before. He gave her a soda and just wanted to talk to her. He thought she was cute and she smiled at him. He didn't grab her or scare her. She wanted to get in his van. He tried to kiss her. She said no and started yelling. He was afraid someone would hear so he covered her mouth, pulled her in back and shook her. He accidentally knocked her out. He was scared and he drove all over. He was going to let her go but she was already dead. So he waited til dark and wrapped her in the blanket and dumped a body. He didn't call for help because he knew nobody would believe he didn't mean to kill her. 

The parents are notified. Father can't believe she was killed for no reason. Mike looks very angry as he says he is sorry.

Fin is glad the case is over. Mike claims to be okay but he wants to know how the families come back from this. They all go to see Rollins but Dodds declines. He asks Olivia if the parents will ever get over this and how she deals with this job when she has a kid. She tells him to go home and talk to someone he loves. Mike stares at the girl's photo.