Mysteries, and Investigators, and Great Old Ones! Oh, My!

Based on this scenario, I have a feeling this group's going to be
losing a lot of sanity after this..

This weekend, I will be kicking off my first new campaign since my Pathfinder one unfortunately fell apart. However, I'm going to be doing something a little different. Instead of my usual fantasy antics, I'm going to go down a darker path for the time being, one that might test my players' sanity.

I'm going to be running Call of Cthulhu. The last time I ran this wonderful game was in high school, and things didn't turn out so well. However, I highly doubt many of us can look back at our early days within the hobby without cringing.

Now that I have more experience under my belt, I'm going to give CoC another crack with a group who seems excited to explore the horrors of the Cthulhu Mythos.

Although I still have some kinks to work out, I already have the basic premise that I'll be using as the foundation for the campaign. The characters will begin their careers investigating the Mythos in 1928 in Arkham, Massachusetts. They will be brought together by a fellow associate who happens to be a professor at the prestigious Miskatonic University. This game will be a micro-campaign, hopefully lasting about four to five sessions. I don't want to give away too much about the specifics since the three people who will be playing in this game know about this blog's existence and I wouldn't want to spoil anything for them, I'll just say the campaign will probably blend some of that science fiction chocolate with Call of Cthulhu's horror chocolate. Also, I have one more thing to ask:

Have you seen the Yellow Sign?