As a Murder She Wrote & Lovecraft fan, I love the ideas here! The characters and story ideas are fantastic.
But I don't think it's fleshed out enough, and I don't personally see the safety elements. Also, I don't think you should just say the true truths--that's something that, in my opinion, the players and Overseer should decide for themselves. Perhaps mark them as ideas?
Great job though--would love to see a more fleshed out version of this!