Sometime in the past I've read a scenario, that I would like to find again. What I remember about the scenario, is that it involved Yog-Sothoth, and a theater.
I think (but I am not 100% sure), that the hook for the scenario is that a friend of the investigators falls down a ladder in the theater, and the investigators start looking into the matter. I think the conclusion is that in the basement of the theater, a cult to Yog-Sothoth operates.