Help!!! Trying to find book from awhile back...

[Briffault]

It's a mystery novel set in the 1800's I believe. It's "bad guy" is a fellow in a black cloak whose pretty mysterious and evil and never says a word until the very end, I think. I doubt it was Sherlock Holmes who was chasing this fellow, not sure though, but at one point the "good guys" ends up searching a beat up old mansion where there's a pudgy, insane butler who has been polishing the silverware even though the master of the house is long gone. This has been driving me up the wall. Thanks so much for your help!