The episode begins with Irina, a babysitter, looking after two little kids, Henry and Ruby, in a busy household. In school, Ruby is shown sitting at the nurse’s office and telling the nurse that her head and her stomach hurts. The nurse finds a bump on Ruby’s head and a bruise on her stomach. She looks worried. Nick and Olivia arrive at the school after they are informed about Ruby’s injuries. Olivia has a talk with Ruby, who says she was pushed by a monster. Ruby’s mom is called in and she tells Olivia and Nick that Irina dropped Ruby off at school and also that Ruby was fine, when she left home in the morning.
Irina when questioned says that Ruby fell down the stairs at home, but said that she wasn’t hurt, which is why she didn’t tell Ruby’s mother anything. Irina says she was in the other room doing laundry, so she didn’t see the accident happen. She is asked about where Henry was and says that he was having waffles in another room and didn’t know anything about the accident. Olivia and team find out that Ruby has suffered multiple injuries in the last year and had visited the E.R a number of times. Cragen tells the team to have a talk with Henry and see what they can find out. Henry says he saw Irina lose her cool with Ruby because she was being difficult and in anger she pushed her.
While Finn is asking around about the Mesners, Ruby’s parents, he finds out from one of Henry’s friends that Henry hates Irina. While looking around in the kids’ room, Nick finds a wooden box hidden in Henry’s closet and in it he finds a matchbox. He opens the box and sees the tip of all the matchsticks missing and then sees the tips kept in another box. During questioning, when Irina is told that it was Henry who said she had pushed Ruby down the stairs, she counters, saying Henry is really mean and Irina calls him the monster.
Olivia and Nick discuss this issue with Viola, the mother, and she admits that Henry resents Ruby and they had to see a counselor because of this. They feel it’s possible Henry is the one who pushed Ruby and Viola agrees with them. She even realizes that all of Ruby’s past injuries weren’t accidents, but Henry’s doing. When Henry is questioned again, he nonchalantly admits that he pushed Ruby and says she didn’t cry much, which means she wasn’t hurt. From the things Henry says, it’s revealed that he derives a sadistic pleasure from hurting Ruby. Tom, the father, tells Olivia that the guidance counselor feels the kids should be allowed to sort the issue out amongst themselves. He says he was like Henry, when he was a kid, but he eventually grew out of it.
Rollins and Finn talk to the guidance counselor, but she doesn’t seem too worried about Henry’s behavior and says Henry is making good progress under her supervision. She says Henry’s parents don’t want to see a psychiatrist because they are afraid he might get labeled. At the office, Olivia and team discuss the issue and come to the conclusion that Henry needs help. They decide to tell Henry’s parents that no charges will be pressed against him, if they agree to take him to see a shrink. Olivia and Rollins talk to the Mesners, but they are adamant about not letting Henry see a shrink. Viola assures them that she has taken a leave of absence from work and will make sure that Henry is taken care of. She also assures them that Henry will never again be left alone with Ruby.
After they leave, Viola goes to Henry’s room to put him to sleep. He says he isn’t tired and doesn’t want to sleep, but Viola insists and in anger Henry takes out a knife, he had hidden under his pillow. Viola orders him to hand it over, but instead he slashes her hand with it. She is shocked and quickly grabs the knife. Henry looks on in anger. At the hospital, while Viola is having her wound looked at, Olivia arrives and Viola defends her son, saying it was her fault that she pissed Henry off. At the Mesner home, Rollins looks on as Tom reprimands Henry for what he did, but instead of feeling any remorse Henry lashes out at Tom, saying the whole thing was Viola’s fault. The commotion wakes up Ruby and Rollins tells Tom to take her back to her room. Rollins says she will stay with Henry and after Tom leaves Henry makes small talk as if nothing has happened, which amazes her.
At the hospital, Olivia tells Viola that they can have Henry evaluated and get him help and this time, Viola seems more open to the idea. Dr. Huang, a psychiatrist, is brought in to evaluate Henry. After a brief meeting, he tells Olivia and team that although he wouldn’t like to label a 10-year-old, Henry, is a psychopath, he ran a test that has revealed Henry is devoid of any emotions and doesn’t feel any sympathy or empathy for anyone. For such severe cases there is a program in a facility in Vermont and the therapist feels Henry should be sent there. He volunteers to talk to Henry’s parents about it and says if they refuse they would be jeopardizing their own lives.
Dr. Huang has a talk with the Messners and after initially resisting they eventually agree. While in office, Olivia gets a call from Henry, who says there is a lot of smoke and he is worried about Ruby. He says his father is at work and he has locked his mother in the laundry room and she wanted him to call 911, but instead he decided to call her. At home, Henry is standing in a room filled with smoke and there is a fire burning in a trash can in the room. He is silently watching Ruby, who is also in the room, and is choking on the smoke.
After the situation has been taken care of, a fireman tells Nick that the fire was deliberately started by Henry using the matches that Nick had seen earlier. Henry had tied Ruby to the bed, so she wouldn’t be able to escape. Henry wasn’t found in the apartment, but the doorman didn’t see him leave, so Nick and team decide to look inside the building. Olivia has a talk with Viola, who says Henry did all this because he was really mad when he was told about the facility. Nick and team go to Henry’s friend Toby’s apartment and find Toby locked in a closet. Toby says Henry stole his father’s gun and left.
Nick arrives at the building play area and sees that Henry has taken a 5-year-old boy hostage using Toby’s father’s gun. Nick talks Henry into letting the kid go, but Henry points the gun at Nick and asks him to stay. While Nick is trying to talk him into giving him the gun, Henry shoots him in the stomach. Nick still manages to wrestle Henry to ground and restrains him, while Olivia arrives with backup. Nick had his vest on, so all he has to contend with is minor injury on his stomach.
While he is at the hospital, Cynthia and Gill arrive to meet him. Cynthia signals Nick to tell Gill that he is his father, something that Nick wanted to do for a while, but couldn’t because Cynthia didn’t want him to. The Messners are informed that Henry will be charged with juvenile delinquency and be locked away till he is 18. When his parents tell Henry about this, he says that he is scared and even begins to cry, but turns out he is only pretending. The episode ends at this point.