Gossip and rumours begin to circulate in the press concerning Sir Andrew Lewis and the Addleton Barrow. Some claim that the Addleton Barrow has been the subject of evil legends as long as anyone can recall; other sources declare that after Sir Lewis opened the barrow in the village of Addleton, a disease struck the village.

Sir Andrew Lewis is a victim of lesions of the skin, headaches, fainting spells, hair loss and eventually his mind is affected, too. Doctors Stamford and Greedom state his condition as an unknown, obscure, tropical disease picked up during his work abroad, and neither doctor is able to save the famous archaeologist from death. Holmes and Watson set out to get to the bottom of the rumours that swirl around this village and it's Black Barrow.