From the publisher:

At the tunnel’s end is an empty suit of armor posed with its arms swept toward the entrance as though welcoming you in with a bow. The corridor leads to a large room scattered with fragments of brass horns and other instruments. Only the enormous pipe organ opposite the entrance has escaped destruction. Above its vast and varicolored keyboard, long pipes crawl in a twisted mass toward the ceiling. To the north is a semicircular mural surrounded by a ring of splinters that were once chairs.

The Dungeon Under the Mountain is a massive dungeon complex extending endlessly below the ground. In a remote past, ancient evil beings dwelled in the area. Now, the remaining of these mysterious evil beings have seized the dungeons and filled it with deadly traps and monsters. Also, many known villains have established their strongholds in the depths of The Dungeon Under the Mountain. Nobody knows why this dungeon is filled by danger, but nobody cares, since this dungeon is the most prized adventure ground of the world. However be warned, adventurers, your life will be not easy here and dozens of self-calling heroes never returned from The Dungeon Under the Mountain!

This is Room 31, Level 1

This product contains one room or one dungeon-based encounter. All the rooms featured here are taken from one of The Dungeon Under the Mountain products, although these products are not necessary, since the encounter can be adapted without effort to any existing dungeon.