The man who was Thursday a nightmare

The Supreme Anarchists Council is dedicated to overthrowing the world order. To keep their identities a secret, each of the members has been named after a day of the week. Gabriel Syme, an eccentric poet, is recruited by Scotland Yard to infiltrate the group. He tracks down the six other men and manages to win a place on the council. But after a bizarre twist of events, Syme quickly realizes that appearances are never what they seem in the dangerous world of the political underground.