Lost Cellar of the Nameless Mage (5E)

From publisher blurb:

Centuries ago, another settlement stood where Dulwich now stands. Much of the area's ancient history has been forgotten—lost to time's remorseless advance and the fading memories of even the longest-lived folk. However, buried or lost fragments of the past yet remain. A merchant, carrying out repairs in the deepest part of his cellar, makes a curious discovery—a stone trapdoor hidden in a sealed-up room—and needs a band of brave adventurers to explore whatever lies below.

This Dungeon Backdrop is designed for the town of Dulwich in the Ashlar mini-campaign setting but can be easily inserted into almost any fantasy campaign.