The Bedlam Detective

From a basement office in London’s notorious Bethlehem Hospital, former policeman and Pinkerton agent Sebastian Becker is sent to interview Sir Owain Lancaster at his country estate. They wealthy industrialist returned alone from a disastrous scientific adventure in the Amazon, claiming that wild beasts killed his family and colleagues. He tells Becker that the same dark creatures have followed him home and are responsible for the deaths of two local girls and rumors of beasts on the moor. But while madmen may see monsters, some monsters hide in plain sight.

http://www.amazon.com/Bedlam-Detective-Novel-Stephen-Gallagher/dp/0307406652/ref=sr_1_1?s=books&ie=UTF8&qid=1435632893&sr=1-1&keywords=Detective+novel