A novella set in the world of the "Rivers of London" series, decades before the first novel. New York City, New York. Meet Augustus Berrycloth-Young - fop, flaneur, and Englishman abroad - as he chronicles the Jazz Age from his perch atop the city that never sleeps. That is, until his old friend Thomas Nightingale arrives, pursuing a rather mysterious affair concerning an old saxophone - which will take Gussie from his warm bed, to the cold shores of Long Island, and down to the jazz clubs where music, magic, and madness haunt the shadows...