Imagine a stratified society where classes are divided not by wealth, nor religion, nor property, but instead by memory. Imagine a world where upper class Duos have two days' worth of memories and plebeian Monos only one day worth. Imagine, too, that the only way to understand your spouse or your child or your mother is to jog your brain with daily e-diaries. And then imagine someone is murdered. How do you find a killer when all who are involved have their memories constantly reset? Claire and Mark are a surprising mixed-marriage that on the surface seems brilliant. Claire is a conscientious Mono housewife, Mark a novelist-turned-MP Duo on the political rise. But when a woman turns up dead, and she is then revealed to be Mark's mistress, their perfectly constructed life begins to fall apart. Told from four different perspectives--Mark, Claire, the detective on the trail, and the victim--Felicia Yap's staggeringly inventive debut leads us on a race against an ever resetting clock to find the killer.