Content Warning: This section of the guide references sexual violence, alcohol use disorder, and mental health conditions. The source text uses outdated and offensive terms for mental health conditions, such as “madness” to describe chaos and uncertainty, which are replicated in this guide only in direct quotes from the source material.

The novel takes place on Kalgash, a world that is lit at any given time by as many as six suns, creating the illusion of perpetual daytime. On a four-sun day, Sheerin 501, a psychologist who works at Saro University, visits Kelaritan 99, the director of a psychiatric institute in Jonglor City, to consult on several cases involving an amusement ride called the Tunnel of Mystery. Sheerin indicates that he would like to interview those who have experienced the ride first to better ascertain the “horrors” of the Tunnel.

Cubello 54, a lawyer who represents the Jonglor Centennial Exposition where the Tunnel of Mystery is based, takes offense to the description of the Tunnel as a “horror.” Nevertheless, Sheerin points out that several people died while traveling through the Tunnel. Kelaritan tries to placate both parties by recalling their shared objective to discern what really happened in the Tunnel.