D&D 5E: Original Adventures Reincarnated #9.5 Hellpits of Nightfang

The Hellpits are a network of three sinkholes located near a bustling trade route and a rural town. These caverns are now occupied by a centuries-old malevolent force, known as Nightfang the vampire, and its followers who carefully target and feed on unsuspecting travelers and locals in order to avoid being discovered by the forces of good. What other mysteries from the past may be hidden within these treacherous Hellpits?