Marzio Montecristo is a grumpy bookseller who prefers fictional murders to real people. He owns The Black Cats Bookshop, home to two feline sleuths, Miss Marple and Poirot, and a weekly book club of self-appointed crime experts. Among them are a Franciscan friar, a widow whose three husbands all died mysteriously in their sleep, and a goth with murder on her mind. Together, they know every twist, every trope and every red herring. But there is a killer afoot. When a terrifying masked criminal begins a real-life murder spree, policewoman Angela Dimase must turn to the unlikeliest of detectives: Marzio’s book club. Drawing on everything they have learnt from years of reading crime fiction, the Tuesday Detectives must use the familiar patterns of mystery novels to solve these bizarre murders.