You'll take my advice and still be on your guard." And now, my long-suffering readers, I will ask you to come away with me for a time, far from the Sussex Manor House of Birlstone, and far also from the year of grace in which we made our eventful journey which ended with the strange story of the man who had been known as John Douglas.
I wish you to journey back some twenty years in time, and westward some thousands of miles in space, that I may lay before you a singular and terrible narrative--so singular and so terrible that you may find it hard to believe that even as I tell it, even so did it occur.
Do not think that I intrude one story before another is finished.

As you read on you will find that this is not so.

And when I have detailed those distant events and you have solved this mystery of the past, we shall meet once more in those rooms on Baker Street, where this, like so many other wonderful happenings, will find its end..