In 1984, exiled author Salvatore Archimboldi accepts the help of a psychotherapist to write his new book. He hopes to transform his traumatic memories into literary genius. But the resulting book, The Truth of Carcosa, is pure evil. Horrified, Archimboldi suppresses the book and wills all traces of it, his correspondence, and any copies to be destroyed.

Long after Archimboldi's death, in a chaotic age of resurgent nationalism and violence, one of the only havens for his work is the ALI, the Archive for Literary Investment, where a biographer and his protégée search through Archimboldi’s correspondence for clues on the evil manuscript as they attempt to stop unscrupulous firms with their own plans for the manuscript.

Told from the perspective of a madman obsessed with The Truth of Carcosa and a ragtag group of friends, it becomes clear that this book is more than a book—and that it might be the answer to a bewildering set of questions:

Why is the Archive so desperate to preserve Archimboldi's work?

Why do so many corporations seem hellbent on seizing any scrap of this mysterious manuscript—and at whatever cost?

What are the strange, dancing monsters that appear wherever Archimboldi's work is discovered?

And who—or what—is the Yellow King?