The following version of this book was used to create this study guide: Fu, Kim. Lesser Known Monsters of the 21st Century. Portland: Tin House, 2022.

Lesser Known Monsters of the 21st Century is a collection of 12 short stories.

In “Pre-Simulation Consultation XF007867,” a customer calls a company that sells virtual reality simulations and tells the operator they would like a simulation in which they can see their deceased mother again. The operator explains that simulations are not allowed to have deceased relatives in them for liability reasons — people would choose to live in the simulation forever. At the end of the story, it is implied that the operator changes their mind and agrees to give the customer the simulation they want.

In “Liddy, First to Fly,” a group of tween or teenage girls is shocked to discover that one of them, Liddy, is growing wings from her ankles. The unnamed narrator, a member of the group, explains that Liddy hopes she can use the wings to fly. The girls go to a cliff overlooking the ocean. Just as Liddy jumps from the cliff, the girls' mothers arrive. The narrator is certain that the mothers will not be able to see the wings, but as Liddy emerges from the ocean, the wings are starkly visible to Liddy's mother and the narrator.

In “Time Cubes,” a depressed woman named Alice lives in a dystopian future world, inside a mall. She never leaves because the effects of climate change make the outside world unpleasant. Alice's therapist recommends she try dating or casual sex to improve her mood. Alice agrees and propositions a man selling time cubes. The time cubes are small boxes containing plant or animal life featuring a knob that can be turned forward or backward. If moved forward, the plant or animal ages quickly and ultimately dies, and if moved backward, the organism becomes younger. After having sex with the time cube salesman, Alice finds a large box with a dial in his spare bedroom. She realizes it is a larger version of the time cubes. She climbs inside the box and turns the dial forward, hoping to end her life. She experiences every emotion she will ever have for her entire life and continues turning the dial, searching for something.

In “#ClimbingNation,” a woman named April attends the memorial service of a man she went to college with, Travis. April did not know Travis in college, but had recently started following him on social media, where he had gotten a large following from sharing his mountain climbing exploits. At the service, April met Travis's sister, Miki, and his friends, Nick and Zach. Nick made it clear to April and Miki that he believed Zach had made a mistake while mountain climbing with Travis, which caused his death, though Zach claimed it was Travis who made a mistake. Miki told the group that Travis was afraid of an apocalypse, and that he had a cabin in a remote location full of supplies and gold, which had been left to Miki when he died. April stayed late into the night and the group fell asleep. April woke up to use the restroom and saw Zach photographing papers on a desk. He then left the house. April told Miki she thought Zach was going to find the cabin and Miki implied that she had made up the story about the cabin to punish Zach for causing her brother's death and then lying about it.

In “Sandman,” a woman named Kelly suffers from insomnia. Her coworker gives her advice about proper sleep hygiene, and when she takes this advice, a cloaked figure appears in her room and breathes sand into her body. She sleeps for hours. Later, Kelly gives up the sleep hygiene routine and the cloaked figure stops visiting. She goes to a movie theater and has a vision of the room filling up with sand. She finds herself in the desert with the cloaked figure. She asks him why he does not visit her every night like he does everyone else and he touches her in a way that suggests, “There, now you're like everyone else” (81). He leaves and Kelly sleeps “the dreamless, nourishing, ungrateful sleep of the innocent” (81).

In “Twenty Hours,” a married couple owns a 3D printer that prints new living bodies for them if they die suddenly. The husband has just killed his wife, Connie, and he has 20 hours until her new body finishes printing. He contemplates the other times he and Connie have killed one another and explains at the end of the story that this experience helps him to not take his wife for granted.

In “The Doll,” a man named Matt recalls an incident from childhood. His neighbors, the Mullen family, died suddenly. The mother and three children succumbed to carbon monoxide poisoning in a rented vacation home. Shortly thereafter, the father hanged himself. Matt and his friends discovered the doll of one of the Mullen children in the family's backyard and took turns bringing it home with them. Each child experienced a supernatural event while the doll was under their roof. Matt had a disturbing vision about his parents suffering from carbon monoxide poisoning and turning into dolls. The children took the doll apart and each was supposed to bury their part in a location not disclosed to the others. Matt did not bury the doll's arm he was given, and it came with him everywhere he lived throughout adulthood.

In “In This Fantasy,” a woman narrates four fantasies she frequently has, including one in which she is a landlady in the 19th century and another in which she is a princess on the eve of revolution.

In “Scissors,” two women act out a sexual performance on stage in front of an audience. One woman is tied to a chair and blindfolded, while the other cuts her clothes off with scissors.

In “June Bugs,” a woman named Martha flees an abusive relationship with her boyfriend Neil and rents a house in the countryside. The house is infested with June bugs. Martha becomes increasingly horrified by the infestation as she reflects on her relationship with Neil. At the end of the story, Neil finds Martha at the house. He points her own gun at her, which she bought to feel safer, but the gun is full of June bugs. They crawl out of the barrel and swarm Neil. Martha imagines putting a pile of dead bugs on the front lawn as “a warning to anyone who might pass” (181).

In “Bridezilla,” a woman named Leah plans to marry her boyfriend Arthur, around the same time that a sea monster is discovered in the ocean. They cannot have the wedding on the beach because of the advanced effects of climate change. They plan to marry on a cruise ship, but Leah flees the wedding. She walks into the ocean and becomes one with the sea monster.

In “Do You Remember Candy,” everyone in the world simultaneously loses their sense of taste. The main character, Allie, creates elaborate sensory experiences that allow people to reexperience their favorite food through the other senses. Allie and her young daughter, Jay, grow increasingly distant from one another, as Jay barely remembers what eating food is like, whereas Allie misses eating very much.