The Thirteen

From publisher blurb: Hudson & Brand, Inquiry Agents of the Obscure for 7th edition Call of Cthulhu is an official Cthulhu by Gaslight consulting detective agency in the style of the extravagant freelancers such as may be found in the stories of the great Sherlock Holmes or Hercule Poirot. This supporting booklet takes a small part of that setting and expands it for the benefit of Keepers who wish to add something a little unusual to their games.