Peter Swanson is back with a chilling and fiendish puzzle of novel, the crime novel everyone will be talking about this Spring. If you're on the list you're marked for death. The envelope is unremarkable. There is no return address. It contains a single, folded, sheet of white paper. The envelope drops through the mail slot like any other piece of post. But for the nine complete strangers who receive it—each of them recognising just one name, their own, on the enclosed list—it will be the most life altering letter they ever receive. It could also be the last, as one by one, they start to meet their end. But why?