The following edition of the text was used in the creation of this study guide: Balle, Solvej. On the Calculation of Volume. Faber, 2025. Kindle AZW file.

Tara Selter, an antique book dealer, is trapped reliving the 18th of November. She has repeated this day 121 times and no longer clearly remembers the 17th or expects to reach the 19th. She lives in a house with her husband, Thomas, and only leaves the guest room when he is out, using his strict routines to avoid him. After he leaves, she goes into town for supplies, takes a bath, and returns to the guest room before he comes home.

Tara recounts the events leading up to the loop. On the 17th of November, she traveled from her hometown of Clairon to Paris for an auction and stayed at the Hotel du Lison. She called Thomas before going to sleep. On her first 18th of November, she bought books, had dinner with her friend Philip and his partner Marie, and helped light a gas heater. She later burned her hand on the heater, returned to the hotel, called Thomas, and went to sleep with her hand in water. When she woke the next morning, her burned hand still hurt. At breakfast she was given the same newspaper as the day before and a guest repeated the same action of dropping a slice of bread. These incidents made her realize that the day was repeating.

Tara confirmed through receipts and newspapers that the date had reset to the 18th of November. Thomas did not remember their previous calls, and the books she had bought were no longer in her hotel room. She found them back for sale and bought them again. At Philip’s shop, Marie did not recognize her, and the gas heater was dusty from a long period of disuse, despite Tara’s burn. Tara then told Thomas that time was repeating, and he believed her. They discussed possible explanations and decided she should return home.

Back in Clairon, Tara gave Thomas a Roman sestertius (coin) and went to bed with the books under her pillow. When she woke, the books remained, but Thomas thought she was still in Paris and was surprised to see her in their bed, confirming the day had reset again. The coin had disappeared. Tara and Thomas verified the date and tried to find a pattern in what reset and what remained, but could not. This cycle repeated for many days. Each morning Thomas forgot, and Tara had to explain the situation again. She convinced him by predicting events like when the rain would stop and when their neighbor would return home. For about sixty days, they spent each repeated day together trying to understand the time loop, which Tara later remembered as a happy period where she felt loved by Thomas before things began to change.

Tara grew increasingly distant from Thomas because he forgot everything each morning while she continued to accumulate memories. She eventually stopped explaining the situation to him and moved into the guest room so he would not know she was there. She monitored his movements and avoided being seen. After five days, Tara left the room and spoke to Thomas again. He believed her, and they spent 27 days studying the repeating day. Tara continued to change physically, such as her burn healing into a scar, while Thomas reset each morning. They could not find a pattern in what disappeared or remained. They tried staying awake through the night. Thomas avoided resetting until he later fell asleep, after which he forgot everything. A second attempt ended with Thomas suddenly resetting mid-day.

They turned the living room into a workspace to track changes but lost hope of finding a solution. After 27 days, Tara decided to stop involving Thomas and began living in the house without his knowledge, moving into the guest room on her 108th 18th of November.

In the present, Tara finishes writing her account on her 124th 18th of November. She accepts the repetition, finds comfort in Thomas’s daily routines, and allows the day to repeat without trying to change it. On her 199th 18th of November, Tara begins secretly following Thomas. She watches him interact with a woman at the post office and feels the loss of no longer sharing a life with him. She decides not to follow him again.

She begins observing the night sky and buys a telescope in Lille. The telescope gives her something to look forward to each night. Tara visits an estate agent, secretly obtains a key, and chooses an empty house to move into on the rue de l’Ermitage. She collects her belongings and leaves without telling Thomas. Living alone, she avoids Thomas’s walking route, spends time in the woods, believes she feels the seasons change, and begins forming a plan.

On her 339th repeated day, Tara deliberately lets Thomas see her and explains everything, asking him to go with her to Paris because she believes nearing one full year of repetitions may allow her to escape. Thomas does not believe her and takes her home. He thinks that she is insane. That night, Tara leaves again despite his attempt to stop her.

On her 349th day, Tara returns to Paris and stays at the Hotel du Lison, where staff treat her as if she has stayed there the night before. She revisits places from the original loop and sees the Roman sestertius again in Philip’s shop.

Tara becomes convinced that when she reaches another November 18th, one year on, something will change. On her 366th 18th of November, she meets Philip, visits his shop, and is introduced again to Marie. They show her an apartment above the shop that they are going to buy. During dinner, Tara tells them about the time loop and tries to prove it, but they don’t believe her. They think she is unstable and ask her to leave. Tara goes back to her hotel and falls asleep, hoping to wake to November 19th.