James is a 17-year-old who believes he is a psychopath, having once burned his hand in a deep fryer to feel something and having been killing animals since he was 15. At school, he encounters Alyssa, a rebellious new schoolmate and decides that he will kill her next. As she takes an interest in him, he feigns romantic interest and the two start dating. When Alyssa asks James to perform cunnilingus on her the next day, he begins preparing his knife and working out how he will kill her. She is late after being stuck at a home garden party where her stepfather tells her it will be better if she left. After that, she visits James and blurts out her desire to leave town with or without him and asks if he is in, wanting him to say yes. Resolving that he could kill her later, he accepts. He punches his father Phil in the face and steals his Mercedes-Benz, something he had always wanted to do. With their newfound freedom, Alyssa and James play laser tag but end up having to dine and dash at a restaurant after realising they have spent all their money. Alyssa suggests they attempt to have sex while driving, but while getting undressed they swerve off the road and crash into a tree. They hitchhike in the van of Martin, a middle-aged man whom Alyssa quickly dislikes. While in the toilets of the restaurant they have stopped at for food, Martin follows James and asks about his burnt hand, before smelling it and putting it on his crotch; James is submissive, despite being disgusted by it. Alyssa sees this and blackmails Martin into giving her his wallet. After booking a hotel room, Alyssa goes to the bathroom and cries, while James waits with his knife by the door, hesitantly. He softens when he hears her crying and puts his knife away; Alyssa calls home and her stepfather Tony answers. He denies her request to speak to her mother, Gwen, implying his dominance over her mother. Alyssa asks James whether he wants her or just goes along with her; he replies that he wants her. She decides to go see her father, Leslie, whom she has not seen since she was 8 years old; James agrees to join her.
Set in the near future, a high-rise apartment building has been newly constructed in the big city. The apartment building has residents from diverse backgrounds, but a new infectious disease breaks out. Because of the outbreak, the high-rise apartment is sealed off. The residents struggle to survive, while stricken with fear and distrust of others. Yoon Sae-Bom (Han Hyo-Joo) is a member of aspecial police squad. She is decisive, determined, and does not easily get rattled. She is excited to move into her new apartment, but, as soon as moves there, she faces a criss. Jung Yi-Hyun (Park Hyung-Sik) is a detective. He is smart and honest. For a long time, he has held romantic feelings for Yoon Sae-Bom. They graduated from the same high school. Jung Yi-Hyun struggles to protect Yoon Sae-Bom and other people. Han Tae-Seok (Jo Woo-Jin) is a lieutenant colonel and belongs to the health service command. He holds a key on the infectious disease outbreak.
The story centers around Devi Vishwakumar (Maitreyi Ramakrishnan), a 15-year-old girl from Sherman Oaks, California. After a socially horrible freshman year, Devi wants to change her social status, but friends, family, and feelings do not make it easy for her. After Devi’s father, Mohan (Sendhil Ramamurthy) passes away, Devi loses the use of her legs for three months. The following year, she tries to deal with her grief, Indian identity and school life, also struggling with her relationship with her mother, Nalini (Poorna Jagannathan), her beautiful cousin, Kamala (Richa Moorjani), her two best friends, Eleanor (Ramona Young) and Fabiola (Lee Rodriguez), her high school crush, Paxton (Darren Barnet), and her nemesis, Ben (Jaren Lewison).