3

The envelope should not have been there. You were quite certain of that. The doors were closed, and the windows were fastened against the cold. Yet there it was on the kitchen table.

It was the same sort of envelope Wesley Snow and David Snowell had received: thick paper, sealed with green wax in the shape of an evergreen. You opened it cautiously.

You have twice prevented December from faltering.
We must ask you once more.
Proceed to Snowfall Manor without delay.
Yours in Tradition,
S. N. Ow

You gathered what you needed and laid everything out on the table: coat, gloves, hat, magnifying glass, newspaper with two holes. You reached for your travelling chess set last of all. When you opened it, you saw that yesterday’s analysis lay exactly as you had left it.

This is a serieshelpmate. Black plays 7 consecutive moves without reply from White, after which White mates in one. For this particular problem, black cannot check at any point (including the 7th move). Here's the position on Lichess. Join our Discord if anything is unclear.