His older sister, Karin, his only near kin, returns reluctantly to their hometown to nurse Mark back from a traumatic head injury.

Shattered by her brother's refusal to recognize her, Karin contacts the cognitive neurologist Gerald Weber, famous for his case histories describing brain disorders.

Weber recognized Mark's condition as a rare case of Capgras syndrome — the delusion that people in one's life are doubles or impostors — and eagerly investigates.

Every section of the book (until a few passages at the end) is so closely focalized through Mark, Karin, or Weber that even the narration of material event is voiced entirely through their cognitive process: the world is nothing more than what these sensibilities assemble, without any appeal to outside authority.In a review in the New York Review of Books, Margaret Atwood described the novel's "underlying sketch" as being from The Wonderful Wizard of Oz.

"[6] On February 28, 2022, a fan brought a copy of the book into a concert by American musician Tyler, The Creator at Little Caesars Arena in Detroit, while embarking on his Call Me If You Get Lost Tour.