Undercover police detective Gabriel Syme is a poet of law; dissident Lucian Gregory is a poet of anarchy. When Syme accompanies Gregory to a meeting of the Central Anarchist Council, he infiltrates the group so successfully as to be promptly elected to the exalted post of Thursday. But discovering another undercover policeman in the anarchists' ranks leads Syme to question matters further. And he must soon face the greatest terror of the Council - its leader, the man named Sunday...