Louisa watches a centaur materialize from a rabbit hole at a train station. The centaur calls to a man in the crowd, who quickly follows him down the rabbit hole. It leads to a fantasy world custom-made just for him. All over the city, others are leaving down their own tailor-made rabbit holes.

Louisa has started work as a temp at a legal office in the city. She meets her boss, Catherine, who informs her that it's been hard to keep staff, as they keep leaving the 'real world.' Later, Louisa enters the filing room of the office and finds one of the cabinets locked with a steel chain, harp music whispering from within. She adds "Filing Cabinets" to her list of "Types of Rabbit Holes."

Day after day, Louisa anxiously waits for her rabbit hole to appear. The city is changing quickly. A bisontaur now works at the newsstand instead of the usual human clerk. One day when Louisa arrives at work, the office is empty, and the locked filing cabinet is open, a harp-song coming out of it—Catherine has gone down her rabbit hole. Louisa stops going into work; she's stopped getting paid. The city is filled with ogres, ghosts, and goblins, and the satyr landlord demands Louisa's rent in gold coins. Unable to pay, she drives out to the suburbs to live at her sister's abandoned house, but she finds it newly inhabited by a swan woman and her family.

Louisa heads to the law firm she used to work at to try to get legal support in reclaiming her sister's house. She finds a male lawyer there—he's the only person in the office. He says it's going to be pretty hard for her to get the house back, as the swan woman's family now has legal ownership of the house. As Louisa gripes to him about not getting her own rabbit hole, the lawyer tells her it's likely because she's read fantasy stories since she was little—so no single fantasy will be enticing enough to keep her entertained forever. It was impossible to craft a tailor-made rabbit hole for her, so she's been left in the human world. But as they look out at a city covered in flying creatures and scaly, tailed construction workers, Louisa realizes that this may just be the perfect world for her—unknown, dangerous, and full of discovery.