It can be found behind the bar counter in the Last Plank.
To whom it may concern,
If you're reading this I'm dead. The Harbor's dead. And likely every damned soul on this island except the Children of Atom are dead. My advice to you is: RUN. This island is cursed. It may be Atom, it may be the Red Death, it may be some angry ghost from the Old World, but it's true. The Fog or the cultists are coming for you.
Leave and tell everyone to leave this cursed island alone for good.