The protagonist, in a vast room within a dome, declares his intention to take a test, interacting with a spectral character named Elia Veranius, a traitor condemned to guiding others in these trials.
It's revealed that the test involves navigating a changing maze, controlled by a bracer in Elia's possession. Elia hands over the bracer to the protagonist, who uses it to manipulate the layout of the labyrinth, made visible by a smaller replica on the ground.
Within the maze roam entities known as Remnants. Elia demonstrates their rapid, standardised movements within the labyrinth. Unable to intervene, the protagonist watches as Elia is "killed" by the Remnants.
The protagonist then gets other spectral figures to repeat the test, observing their movements, improving his understanding of the maze, and developing potential ways through it.
Despite fears and doubts, the protagonist decides to take the test himself. He enters the huge, ominous Labyrinth, effectively locking himself in, and begins navigating.
In the maze, he finds the body of a schoolmate, Belli, which frightens and disorients him. Nonetheless, he continues, evading Remnants with quick thinking and adaptations on the bracer.
Finally, he reaches the end of the Labyrinth, narrowly escaping a Remnant by hurtling through the exit just before it reaches him. After removing the bracer and dislodging the last traces of the Labyrinth, he is left in silence.