Hey Maze!
SPOILERS BELOW!!!!!
DO NOT READ IF YOU DO NOT WANT SOME ELEMENTS OF THE CALL OF CTHULHU ADVENTURE "MURDER OF CROWS" TO BE SPOILED!!!!
Thanks man. I absolutely LOOOOVE GMing Call of Cthulhu. The Murder of Crows adventure was designed to be a "low impact" adventure with very little actual Cthulhu mythos in it. It was designed to be more of a creepy investigative adventure. I wanted to punch it up just a bit by adding in the monster at the very end.
Some of the more creepy elements were designed to occur in the Walker mansion, but they never went into the mansion, (which is fine cause were ran slightly longer than our available game time slot even without going in there). All of the animals were being controlled by Prescott Walker and the necklace he was wearing. In reality, the necklace was a cleverly designed Mi-go device.
For whatever reason, Prescott Walker was such a low threat, it was assumed by the adventure's author that the players would subdue him, and then take the necklace. At which point, the player/character with the necklace would become "possessed" by the necklace and become the "villain" of the story just like Prescott was. In order for that to happen, the player/character who takes the necklace is supposed to fail a roll of some sort, but in my game Tom's character succeeded in his roll, so he was able to take the necklace without become possessed. And thus ended our allotted game time, and thus ended our game.
It was super-fun to play/run that game though. I had a ton of fun with the NPCs. I would run this adventure again, but hopefully I would do a better job of amping up the creep factor.