Word from Oakhurst - Tier 4 Adventure

A young black dragonborn approaches you, and after verifying you are who you say you are produces a waxed scroll case. They slide a rolled missive to you and ask for directions to the nearest inn. The wax seal is a single oak tree with a massive canopy. The message is simple: "Oakhurst is calling in a long overdue favor. We need you help. We found something underground. We think it's related to him..."