From the back cover:
For two to six players, Scritch Scratch can be played in one or two sessions. Set in the modern-day, in a quiet valley somewhere in the north of England, this adventure concerns the demise of an age-old tradition in the quaint village of Muscoby—and the consequences of forgetting the Old Ways.
Muscoby has never not had a rat catcher. Old Gurteen has been carrying on the tradition in the village, but recently he was involved in an accident and is now hospitalized. With Old Gurteen away, who will ensure the rat population is kept in check?
Six pre-generated investigators are provided for use with this scenario, which is a great introduction to Call of Cthulhu while also being a suitably mysterious and horrific evening of fun for more experienced players.