How do you solve a murder when you can only remember yesterday? Imagine a world in which classes are divided not by wealth or religion but by how much each group can remember. Monos, the majority, have only one day´s worth of memory; elite Duos have two. In this stratified society, where Monos are excluded from holding high office and demanding jobs, Claire and Mark are a rare mixed marriage. Clare is a conscientious Mono housewife, Mark a novelist-turned-politician Duo on the rise. They are a shining example of a new vision of tolerance and equality-until... A beautiful woman is found dead, her body dumped in England´s River Cam. The woman is Mark´s mistress, and he is the prime suspect in her murder. The detective investigating the case has secrets of his own. So did the victim. And when both the investigator´s and the suspect´s memories are constantly erased -- how can anyone learn the truth? Told from four different perspectives, that of Mark, Claire, the detective on the case, and the victim -- Felicia Yap´s staggeringly inventive debut leads us on a race against an ever-resetting clock to find the killer. With the science-fiction world-building of Philip K. Dick and the twisted ingenuity of Memento, Yesterday is a thriller you´ll never forget.