"The module takes place in a large cavern that is part of an extensive underground cave network. It can be used as a side-trek encounter in the Undermountain or Night Below campaign." -- from the adventure. Includes a small keyed map of the cavern.
Welcome to the dark heart of Forlorn, brooding Castle Tristenoira. In this stony ruin, ghosts rule the night and mortals quake in fear until morning comes. Few enter the gloomy halls of this keep and live to recross its crumbling drawbridge. Those adventurers who have survived such a foray tell eerie tales of half-seen shapes, shifting hallways, and ominous shambling beasts. "All is not as it seem sin Castle Tristenoira," they say through trembling lips. "Time itself has no meaning there." This adventure booklet is set entirely within the confines of Castle Tristenoira, and it serves as a climax to Melancholy Meetings, the other 32-page adventure booklet found in the Castles Forlorn boxed set. Eve of Sorrows brings together adventurers and the inhabitants of the castles three, providing a chance to solve several mysteries of this lonely domain. Included in Castles Forlorn - https://www.adventurelookup.com/adventures/castles-forlorn TSR 1088