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.