Nine Lives by Peter Swanson

The envelope is unremarkable. There is no return address.
It contains a single, folded sheet of white paper.

MATTHEW BEAUMONT
JAY COATES
ETHAN DART
CAROLINE GEDDES
FRANK HOPKINS
ALISON HORNE
ARTHUR KRUSE
JACK RADEBAUGH
JESSICA WINSLOW

The envelope drops through the mailslot like any other piece of post. But for the nine complete strangers who receive one - each of them recognising only their own name 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?