Cthulhu Casebooks: Sherlock Holmes Miskatonic Monstrosities - James Lovegrove

This book is a crossover fiction telling how the famous detectives Sherlock Holmes and Dr. John Watson battled eldritch entities from the Lovecraftian canon. Holmes and Watson investigate a lunatic held in the infamous Bedlam asylum who speaks the language of the Old Ones and go on a voyage to New England to investigate monstrous events.