In a dystopian future, a virus has wiped out the majority of the Earth's population, leaving only one walled, protected city-state called Bregna. Governed by a congress of scientists, Bregna is portrayed as utopian but is rife with strife and discontent among its citizens due to unexplained disappearances and a sense of imprisonment. Amidst this seemingly peaceful society, an underground rebel group known as the Monicans operates, fighting against the authoritarian regime. The protagonist is a skilled and acrobatic assassin who is a key member of this rebellion.

Tasked with a high-stakes mission, the protagonist is set to assassinate the government's leader, believing him to be the source of Bregna's turmoil. As she delves deeper into her mission, she begins to encounter various puzzles and anomalies that suggest a different reality from the one presented to her. This discovery leads to questioning her own beliefs and the goals of the Monicans. An enigmatic figure with ties to her past emerges, and she finds herself entangled in a complex web of conspiracy that forces her to confront her identity and the true nature of her society.