Morgan, who is autistic and nonbinary, lives in Casswell Park, a large, centuries-old Haunted House, with their Family of Choice of seven other people, all of whom have been rejected for being queer or neurodivergent. The eight of them have turned their home into a sanctuary for ghosts, and dozens of them now live there. One day an old man delivers eighteen bottles, each with a ghost trapped inside, that have been in his family for centuries. When Morgan starts opening the bottles, they discover a pendant in one of them. Shortly afterwards, the ghosts and humans of Casswell Park start being subjected to strange supernatural attacks by an entity called the ghost eater.
Sanctuary contains examples of:
- 20 Minutes into the Past: The book takes place in the winter and early spring of what is revealed late in the story to be 2018.
- Abandoned Hospital: Pittlow Asylum is a haunted mental institution that was purchased by a company that wants to give haunted asylum tours. Most complaints are from disability rights activists who don't want a place where mentally ill people were imprisoned and tortured to be turned into a spooky tourist attraction, but Morgan objects because they don't want the ghosts' privacy to be invaded by people who see them as freaks. Eventually someone else opens their home to the asylum ghosts, so they can get away from the tourists.
- Amicable Exes: Vinnie and their ex Caleb are still good friends, even though their relationship has been dead for years.
- And I Must Scream: Ghost collectors like to keep ghosts trapped in bottles, while they're still fully conscious. The eighteen bottles delivered to Casswell Park have all been stoppered up for centuries.
- Basement-Dweller: Morgan lived with their parents until their mid twenties. Part of the reason they moved into Casswell Park was because they were worried about what would happen to them when their parents died.
- Death by Childbirth: Henrietta Casswell, a ghost who dates back to when Casswell Park was a family home, died this way.
- Disneyland Dad: Caleb is a type 1. He works as a long haul airline pilot, which means that he gets few opportunities to see his and Vinnie's ten-year-old son Theo, who lives with Vinnie in Casswell Park. When he does get a few days with Theo, he always takes him someplace fun, like Alton Towers, and when he visits, he always brings gifts that he picked up in his travels.
- Dumb Struck: In moments of stress, Morgan loses speech and types to communicate. After the defeat of the ghost eater, they can't talk for two days.
- For Science!: William Casswell aka the ghost eater subjected ghosts to all sorts of torments, including being cut in half, in order to learn about and categorize them.
- Grand Theft Me: Because Araminta is wearing the pendant, the ghost eater is able to possess her and force her to destroy her own studio. Then he steals her corporeality, leaving her as a ghost while he becomes almost solid.
- Immortality Seeker: The ghost eater wants to extend his life indefinitely by stealing corporeality from ghosts.
- Interrupted Suicide: Holly stays up for days due to both her homework and the problems afflicting Casswell Park. When she's too exhausted to study for a biology exam, she's convinced that she'll fail, and because she sees her academic ability as her only redeeming quality, she attempts suicide by overdosing on pills. Theo sees her bent over the toilet surrounded by empty pill packets and runs to fetch the adults. Morgan gives her glasses of warm salt water to make her throw up all the pills. Vinnie decides to keep her at home and put her on suicide watch instead of taking her to the hospital for fear that the doctors will return her to her Abusive Parents.
- Invisible to Normals: Morgan and their friends have always been able to see ghosts, although Morgan only saw a few before they moved into Casswell Park. The ability to see ghosts runs in Morgan's family, and they never thought it was unusual.
- Mind over Matter: Denny is telekinetic. He mostly moves light objects like pens, until the final battle, when he draws on the mental equivalent of hysterical strength to rip a door off its hinges and slam it into the ghost eater, then drops a wardrobe on him, immobilizing him.
- My Eyes Are Up Here: The ghost hunter Keira stares at Morgan's girlfriend Araminta's chest. Araminta says, "Um, my face is up here." Keira panics, mumbles that she was looking at Araminta's pendant, and flees almost in tears, causing Araminta to feel guilty.
- O.O.C. Is Serious Business: Denny is old enough to be uncomfortable with any computer that doesn't use a command line interface. He can participate in the house's group chat, but every time he writes anything, he agonizes over whether he's saying the right things, and his grammar is always impeccable. So when Morgan gets the message "somethng wierd down here," they and Araminta immediately know something major has happened.
- Overworked Sleep: Morgan is trying to study the ancient book they found under the ripped-up floorboards of a destroyed room, but they're so exhausted from everything that's been happening that they fall asleep before midnight, which they almost never do. They wake up a few hours later.
- Poltergeist: Poltergeists are fairly uncommon. Denny speculates that they're the ghosts of people with telekinesis, like himself. Hannah, one of the ghosts from the bottles, reacts to the ghost eater's attacks by rattling floorboards.
- Post-Victory Collapse: After the fight with the ghost eater, Morgan falls asleep sitting up in the hallway. Afterwards, they sleep for over a day and then spend several days hiding in their room, too exhausted for any human interaction.
- Psychometry: Morgan can detect lingering sensations attached to places and objects, usually just the knowledge that something good or bad has happened here, but occasionally flashes of someone else's memory.
- Ransacked Room: Araminta, a talented artist, finds that her studio has been ransacked, with paint squeezed out of tubes, tubs of brushes and pencils turned upside down, pastels broken and ground into the carpet, and the messages "YOU WILL BE KEPT AS PRISONER," "YOU WILL DIE AS WE HAVE DIED," "WE WILL ALL FADE AND GO," and "GET OUT. YOU DON'T BELONG HERE" written on the canvases. Araminta is horrified, not only because of the threats but also because her trauma makes her an intensely private person who rarely even lets Morgan into the studio, and because she can't afford to buy new paints and canvases.
- Sealed Evil in a Can: In 1708, Isobel trapped the ghost eater in a pendant, which she put in a glass bottle which she stoppered shut. She sent it and all the ghost bottles to her brother with strict instructions not to open any of them. The ghost eater remained trapped until Morgan opened the bottle three centuries later.
- Sensory Overload: Morgan doesn't go out by themself because all the sensory input causes them to space out and wander aimlessly, putting them at risk of getting lost or hit by a car. Whenever they leave the house, someone accompanies them.
- Snowball Fight: When a snowfall shuts down all the schools, Morgan, Theo, Holly, Araminta, and Denny all get in a huge snowball fight. Even some of the ghosts join in by swooping around to distract the players.
- Soul Eating: The ghost eater devours three ghosts and parts of others in order to gain corporeality.
- String Theory: Saeed sets up a corkboard covered in photos, notes, and string to show the others his research on Keira and Logan, the two ghost hunters who broke into Casswell Park to harass the ghosts.
- Too Unhappy to Be Hungry: Half the people in the house respond to the ghost eater's attacks by becoming ravenously hungry, while the other half, including Morgan, lose most of their appetites.
- Wanted a Gender-Conforming Child: Holly is a teenager whose Abusive Parents enforced extremely strict gender roles on her and her brothers. Eventually she couldn't take it anymore, so she ran away and now lives in Casswell Park. She still goes to school, and she has friends who know about her living situation, so her parents could presumably track her down if they wanted, but they never do.
- Working Out Their Emotions: Morgan deals with stressful situations by cleaning and organizing almost everything in the house. After Holly's suicide attempt, Vinnie calms Morgan down by having them clean dishes.
