Letter to Bonville is a written note found in Dishonored 2.
The last man had made it all the way north to Meya, if you can believe it, and was recovering at a Tyvian asylum for the poor, claiming to have seen all manner of strange things on the night of Stilton's last social gathering. He even described an exotic, hooded figure visiting the manor. Perhaps someone connected to Stilton's disappearance. Such matters are best left to military men such as yourself, I suppose.
I still have your bank agent's name and address. Rest assured, your final payment will be delivered soon. I'm also sending a small flask of a liquor that is close to my heart, made from the pomace left over after wine grapes have been pressed. Please think of me as you enjoy.