The Cthulhu Casebooks - Sherlock Holmes and the Miskatonic Monstrosities

It is the spring of 1895, and more than a decade of combating eldritch entities has cost Dr John Watson his beloved wife Mary, and nearly broken the health of Sherlock Holmes. Yet the companions do not hesitate when they are called to the infamous Bedlam lunatic asylum, where they find an inmate speaking in R’lyehian, the language of the Old Ones. Moreover, the man is horribly scarred and has no memory of who he is.
The detectives discover that the inmate was once a scientist, a student of Misk