From the Chaosium website:
A Mini-Campaign for Call of Cthulhu
The fight against the forces of the Mythos is fraught with peril and it is all too easy for even the strongest will to be tempted by the dark secrets whispered in the cold and empty places of the world.
This monograph presents a series of adventures intended to provide a coherent, yet flexible, mini-campaign. These adventures center on Reginald Preston, a devoted foe of the Mythos who falls victim to its temptations.