The Man Who Was Thursday - A Nightmare by G.K. Chesterton | Classic Mystery Thriller Novel | Perfect for Book Clubs & Literature Lovers" (Note: Since the original title appears to be a book title, I've maintained the original title format while adding relevant SEO elements and usage scenarios. If this is actually a product rather than a book, please provide more details about the item for proper optimization.)

Inspired by the G.K. Chesterton novel of the same name, The Man who was Thursday is a thriller set in the world of Detective Gabriel Syme, as he tries to infiltrate the Central Anarchist Council. An undercover Syme makes his way into a secret meeting of the anarchists and becomes 'Thursday'; one of the seven key figures in the council. Syme soon learns, however, that he is not the only one in disguise, and then the real nightmare begins.