Trail of Cthulhu RPG: Core Rulebook
You uncover mysteries in dusty libraries and bloody crime scenes. You walk the mean streets of Chicago or hack through the jungles of the South Pacific. You battle vile cults, or recoil in terror at the alien enormities they worship. You follow the clues wherever they lead, whatever the cost in life or sanity. But do you dare to follow… the Trail of Cthulhu.
Trail of Cthulhu is a complete game of investigative horror set in the 1930s based on the work of HP Lovecraft. The game uses an adapted version of the GUMSHOE system which offers a laser-like focus on investigation, with characters driven to explore and investigate, even at the expense of their own health and sanity.