The episode begins with Leonard Brooks telling his doctor about the first fire he started and how he felt he was in control. He also wasn’t scared anymore and there was no going back. Next, a couple is making out in the elevator and Leonard is watching them on a tab. Moments later, a woman enters the elevator and the couples exit. The woman then tries to open the elevator door; but it is stuck. She smells something weird and is traumatized to see that the roof of the elevator is on fire. She calls for help; but none arrives; and a calm Leonard is watching all this. Next, the team arrives at the scene and Leonard watches them enter the building. He then leaves.
They find the woman’s charred body lying on the floor and Mac deduces that the pipes running across the roof were the source of the fire. Don arrives and declares that he victim’s name is Rita Lawman and she freelanced a couple of times. They find security footage where they are told that there was an unscheduled visit by a repair man and they see that it was Leonard. The team goes to Leonard’s apartment but Leonard has already cleared out. Don wonders what game Leonard is playing. Mac says, “Whatever it is, he had fifteen long years to plan it”. Later, Don informs Mac that all routes around the city have been covered. Leonard has no friends or family; that makes him even more unpredictable. Just then the phone in Leonard’s apartment rings. It is Leonard and he asks for Mac.
He tells that the press is wrong about him. He says that the victim is anything but innocent. Danny and Monroe examine the elevator for evidence. Monroe finds a hidden camera. Sid examines the charred Rita and he is surprised that despite the severe external damage, the internal structure remains unscathed. So, the COD was hypothermia. This means she was boiled not burnt. The heat from infra red radiation was strong enough kill her and not a single flame touched her. The elevator walls kept the heat contained. Hawkes finds a medallion on Rita’s body and it has an encryption that says: to Jen, with love. Mac is looking at the security footage and Jo walks in saying that Leonard always damaged property.
Wonder why he has started hurting people? Maybe torture and murder is his new found choice. They need to get inside Leonard’s head to find what he is planning next. Mac fears that if they don’t catch him soon, there could be more deaths. Next, Detective Jamie Lovato starts her first day at work. Don is impressed with her style. She has been transferred from narcotics to homicide as her cover was blown. Mac arrives and Don tells him that Rita was living under an alias. Rita isn’t her real name. And Jen seems to be living off the grid for the past 12 years; so, she was hiding from Leonard. They now need to make a connection. Next, Leonard is in a park, and he is watching a man sitting on a bench and eating his sandwich.
He takes a bit and finds that there is an odd taste. He drinks water and he begins to choke and instantly falls to the ground. Later, the man is in Sid’s lab; dead. He is Jimmy Clarke. EMT treated him for myocardial infarction but was unsuccessful. But Sid says that it wasn’t an infraction; it was a hypoglycemic shock which was carefully planned and induced. COD was due to being burnt alive from the inside. But Sid still doesn’t know what Jimmy swallowed which ignited his stomach. Next, Don shows Mac the footage from the surveillance cameras in the park. They see that Leonard stuck around to watch the show. Mac wants to know where he walked out to from the park. It is clear that his motive is strictly personal. Jamie arrives and says that Jimmy and Rita were connected.
Jimmy lost his parents at the age of two and Rita was a nurse. She could be the one who the State appointed to take care of Jimmy. But that is impossible to find out without knowing Rita’s real name. Jo is trying to build Leonard’s psych profile by looking at his therapy session recordings from the prison. Monroe finds out what exactly killed Jimmy Clarke; simple chemistry! Leonard added a little cesium (an alkaline substance) to the mayonnaise, which reacts with water. When Jimmy washed the funny taste down with water, the mayo reached the stomach and came in contact with the digestive juices (hydrochloric acid) and instantly caught fire. The sandwich wrapper came from a deli which Jimmy went to every day to get a sandwich.
The deli guy said that he appointed a new counter guy last week and the description matches with Leonard’s. So Leonard watched Jimmy and exploited his routine. Don and Jamie find out that Rita’s original name was Jennifer Brooks and Jimmy was under her care. So it seems that Leonard killed his own mother and foster brother. They infer something terrible must have happened after Leonard’s father’s death, for Leonard to start setting fires and kill his mother and foster brother. Danny arrives and tells them that Jennifer had another foster child, Rachael Nelson. Adam runs a check on Rachael and finds out that she is now Rachael Moore and she is in rehab for 90 days as per court orders. Next, Leonard pours down some chemicals like ammonia and bleach down the AC duct of the rehab which causes smoke.
When the team arrives they don’t find Rachael in the rehab. We see that Rachael is in the trunk of a car and the tail lights are on. Rachael is screaming for help. Jo is still going through the tapes. She finds something and tells Mac about one of Leonard’s nightmares, where he is the deer and he is being hunted; this refers to his mom and brother. Hawkes arrives and says that the chemicals that were found were degraded and were about ten years old. They figure out that his mom was a burn ward nurse at St. Aiden’s and it has been abandoned for the last ten years. If Leonard is setting fire to his past, he would probably end it at the same place. They arrive at the abandoned hospital and Leonard is preparing to set Rachel on fire.
Rachael asks him for forgiveness. Leonard tells her that she could have helped him when his mother tortured him and beat him up. But Rachael tells him that she was only seven. Leonard doesn’t want to listen to anything and lights the lighter. Mac arrives and asks him to put off the fire. Don tackles Leonard from behind and they arrest him. Rachael is safe but she admits to Mac that Leonard is right; she should have done something. At the station, Leonard tells Jo and Mac how his mother kept him in the hot basement and continuously beat him up. Jimmy showed up after his father’s death and he too beat him up; but his mother hurt him the most. She used to take him to the hospital and he would see how much she cared for the patients in her ward.
All he wanted was to be loved by her. It is the events of our lives that make us and it is the choices that we make that shape us. Mac tells Leonard that he made the wrong choice. Next, Jamie gets her new desk. Leonard is in prison and he is reading a book. He feels the sunlight coming into the room. He then holds his specs over the book and uses the converging lens to set fire to the book. The episode ends.