London, 1946. Gabriel Book is an erudite and unconventional London bookseller married to Trottie, the owner of the wallpaper shop next door. He is also a sleuth who uses the chaotic riches of his stock to crack the puzzling cases that come his way.

He does not work alone. Book's shop is a magnet for waifs and strays - some of whom bring mysteries of their own to his door. There's Nora, sometime bookseller and true crime enthusiast; Dog, connoisseur of ginger biscuits and then Jack, whose arrival at the shop forces Book to confront a loose end from his own past.