Madness in the Undermarch

From the introduction:

Recently merchants and caravans traveling the Undermarch have been waylaid. The merchants left dead and their goods stolen. The Undermarch Officers, appointed by the Dwarf King’s military, have been unable to locate this new threat. The Dwarf King has decided to look for help from groups of adventurers and mercenaries to stifle this new threat, not wanting to allocate resources from elsewhere in the Dwarven empire that are needed to defend against the encroachment of the Orcs, the denizens of Hell Marsh, and the threats from the Giantwalk above the Undermarch or from the poisoned Drow residing deep below in the Underworld.

From the introduction:

For 3rd level characters.