Gabriel Syme, a poet, challenges an anarchist who preaches in the public square, then finds himself as a special guest to an underground meeting of the anarchist movement. Their task that night, to elect a new “Thursday” to the dreadful Council of Days, the high council of anarchy, led by President Sunday. These are the seven worst men in the world, each named for a day of the week. Gabriel, secretly an undercover detective for Scotland Yard, manages to get himself elected to the post of Thursday, and soon finds himself on a ship down the river Thames, bound for his first meeting of the Council of Days. He has no idea how the adventures that follow will affect him, each turn more bizarre than the one before, each twisting his understanding of the universe from upside down to right-side up again.