Diggin' Up the World

From the publisher:

The small town of Aylesbury is buzzing over the sudden madness of two of its local boys: Kurt Caughey and Richard Doggett. Once they were two layabouts who did nothing but sit about their homes and listen to the radio. Now, they have taken it upon themselves to dig compulsively, spending sixteen-hour days turning a backyard into a construction zone. No one is certain why this is the case.

This scenario is a 1920s Call of Cthulhu scenario for a small group of investigators, preferably one of whom will have a high Medicine or Biology skill.