**Winner of the Capital Crimes Reader Award for Debut Book of the Year** SHORTLISTED FOR THE GLASS BELL AWARD AND THE BARRY AWARD FOR BEST FIRST NOVEL THE BIGGEST MYSTERY CAN BE MURDER TO SOLVE . . . DISCOVER THE YEAR'S MOST ORIGINAL CRIME NOVEL 'One of the year's most entertaining crime novels' SUNDAY TIMES, CRIME BOOK OF THE MONTH 'When did you last read a genuinely original thriller? The wait is over' A. J. FINN 'An elegantly structured, intellectually challenging and completely unique thriller that grips like a vice' SOPHIE HANNAH _______ All murder mysteries follow a simple set of rules. In the 1930s, Grant McAllister, a mathematics professor turned author, worked them out, hiding their secrets in a book of crime stories. Then Grant disappeared. Julia Hart has finally tracked him down. She wants to know what happened to him. But she's about to discover that a good mystery can be murder to solve . . . _______ 'One of the most creative detective novels of the year . . . If not of all time' Samantha Downing 'Intelligent and inventive . . . It's the most fun I've had in ages' Cathy Rentzenbrink 'So, so clever . . . Agatha Christie would take her hat off to this one - bravo!' Sarah Pinborough