From publisher blurb:
In Exploration of Willow Castle, a group of level-7 adventurers learns about the Willows, an opulent family in the region. Rumor has it that something odd happened at the castle. The same rumors describe horrible screams, monsters, and missing people. The Dragonhorn Road Inn is located near the castle. The owner, a dwarf called Lazaro Flint, knows more about this, though his information is vague and subjective.
Augustus Willow, explorer and researcher, is the culprit of his family's demise. He made a deal with a demon imprisoned in a malachite urn decades ago, when he was alive. In exchange for a life of luxury and vices with no consequence on his health, Augustus agreed to pay with the souls of his family, who currently lie dead in the crypts beneath the castle. His restless and angered soul has risen the dead in the crypts. Someone must stop this.