Everything, Everything is a coming-of-age story about a teenage girl suffering from a life-threatening immunodeficiency disorder, who, unable to leave her house, dreams of a life outside and of truly being alive. Maddy occupies her time reading and enduring constant health checks by her mother and her nurse Carla, but she escapes the monotony of her life by creating fanciful imaginings of the world outside and how she might fit into it. When Maddy uses the astronaut in her dioramas and visualizes him in her dreams and musings, it’s clear she, too, is observing the world from the outside. She craves a normal life and feels trapped by her illness, destined for a life of solitude, routine, and loneliness.

When new neighbors move in next door, Maddy is drawn to watching them through her window. She sees Olly and is intrigued by his presence and the mystery he exudes. Olly too seeks the escape of finding a friend and building a connection outside of his family. Maddy and Olly begin communicating wordlessly through their windows, but their friendship eventually evolves into messaging, which opens the door to Olly and Maddy sharing more personal details including Maddy’s illness. The nature of their early interactions, hidden behind their keyboards, gives both Maddy and Olly relative anonymity, which allows them to be more vulnerable than they might be in person. Their mutual acceptance deepens their friendship quickly. Maddy realizes that she’s falling for Olly and although it scares her, she wants more.

The major conflict of the story is Maddy’s desire to live a normal life despite her understanding that she will die if she leaves the house. Although she rationally knows it is a risk, Maddy is determined to convince Carla that she could meet Olly in person as long as they don’t touch each other. Although Carla knows the rules and knows the risks for Maddy, she is blinded by her pain at her own daughter’s distance, so she bends to Maddy’s persistence and allows it. The meetings with Olly intensify the relationship and feelings of love emerge, constantly under the scrutiny of what it all means and how any moment in their lives affects all subsequent moments. Maddy is equally exhilarated and frightened by her relationship with Olly and the feelings that she is grappling with.

Following a breach of the house to go outside to Olly’s aid, Maddy does not get sick. Once again under quarantine, Maddy realizes that her feelings are not just those of teenage angst; she is not just lonely, but alone. This may not have bothered her in the beginning, but now that she has had a taste of freedom, she craves more. This prompts Maddy to make the bold decision to run away to Hawaii with Olly, even if she fears she might die from it. The adventure in Hawaii is picture-perfect for Maddy and Olly, but it leads up to what the reader may think is the climax of the story: Maddy becomes severely ill and her heart stops. However, Maddy survives the incident and the story continues, with her choosing life over love and banishing Olly to protect herself from heartbreak.

With Maddy back at home, under the care of her mother, who has become very fragile physically and emotionally, the reader expects that Maddy’s life will revert to her routine and she will continue her solitary life. However, the story has a twist: In Chapter 112, Maddy receives an email and learns that she likely does not, in fact, have SCID. The next chapters reveal that Maddy’s mother faked her extreme diagnosis in an attempt to prevent Maddy from going out into the world, where she might be harmed or choose to leave to live her own life. This climactic revelation throws Maddy into confusion and internal conflict; she locks herself in her room and refuses to talk with her mother.

It takes Carla, the only adult Maddy can trust, to persuade Maddy to try and forgive her mother. Maddy reflects on her journey with Olly, chaos theory, and how the gently spinning universe can influence one moment and the next, and she concludes that nothing can become everything. Conversely, she considers the love and the loss that her mother has suffered and recognizes that everything became nothing. It is at this moment that Maddy forgives her mother and moves on to begin her life. The story ends with Maddy reconnecting with Olly over her edition of The Little Prince. It is her favorite book because its meaning changes every time she reads it, just like Maddy’s perspective on how love has changed throughout her journey to this moment.