From the introduction:
This adventure is a quite challenging one. Players must really think their way through situations, and Keepers can have a lot of fun toying and misleading the players without putting them in any danger. This adventure is probably best suited for experienced [Call of Cthulhu] players. They are more likely to yield on caution's side, whereas players of hack-and-slay games may rush in. Should this occur, the Keeper should throw some heat at them, be it law enforcement or a mild seizure.
A Call of Cthulhu Adventure, recommended for three to five experienced players, set in 1962.