After the sudden and tragic death of his young daughter, Brendan begins to notice discrepancies in his memories and the world around him, leading him to uncover the concept of the Mandela Effect. Obsessed with the idea that something larger is manipulating reality, he dives deep into research, discovering various instances where collective memories of historical events, products, and cultural phenomena differ from actual historical records. His wife, Claire, struggles to reconcile his growing obsession with their shared grief. As Brendan's fixation intensifies, he encounters others who share similar experiences and questions if their altered memories point to parallel universes or a simulated reality.

Brendan's relentless search for the truth leads him to a reclusive scientist who suggests drastic measures to expose the potential manipulation of reality. Desperate for answers, Brendan navigates a series of increasingly disorienting and surreal experiences, pushing the boundaries of his perception and sanity. As he delves further into the nature of existence, his relationships strain under the weight of his discoveries and his spiraling mental state. The story weaves an intricate tapestry of reality and illusion, questioning the very fabric of what is real as Brendan battles to make sense of his new understanding of the world.