A background supplement for 1920s Call of Cthulhu, describing the New England village of Dunwich and its environs. Contains the scenario 'Return to Dunwich'.
From the back cover:
"Deviant, derelict, degenerate, demented, deleterious
Dunwich is a small village located along the Miskatonic, upriver from Arkham. Until 1806, Dunwich was a thriving community, boasting many mills and the powerful Whateley family.
Those among the Whateleys came to know dark secrets about the world, and they fell into the worship of unwholesome creatures from other times and places. Retreating to the hills and forests surrounding the town, they betrayed their uncorrupted kin.
Prosperity fled, and a dark despair seized the people. What remains is a skeleton town, mills closed, its citizens without hope or future. However, the secrets of the Mythos survive, to be discovered by brave and enterprising investigators.
Return to Dunwich contains extensive background information about a town originally created and described by H.P. Lovecraft in his terrifying tales of horror. Pertinent buildings, useful people, and important locations are described in depth. A 17x22" map of Dunwich Country depicts the area for miles around. Two new scenarios are included: one introductory and the other suitable for many evenings of play. Various links and leads to Arkham are included; possession of Arkham Unveiled is useful but not necessary."