Crimson Letters is a great scenario if you and your group likes investigation, puzzles, and quirky NPCs. It plays like a whodunnit murder mystery, with the investigators trying to figure out how a Miskatonic University professor died in his locked office of a strange seizure, and where the valuable papers have gone that he was appraising. With a full cast of interesting, distinct and memorable NPCs, an emerging monster, a lot of handouts available online, and an exploration of the city of Arkham, it allows for a lot of creativity and fun for both players and keepers. And to top it off, as a keeper you get to pick who the culprit is!