All the dangers of Saventh-Yhi, the city of the lost jungle since the beginning of the modern era, pale in comparison to the terrors that lurk beneath its shattered streets. Under the ancient ruins, a kingdom of darkness and monsters rots, against which Saventh-Yhi has long been on guard. In the eternal night of this lower realm, adventurers venture, facing the degenerate heirs of a lost empire, the inhabitants of darkness (who worship the infernal) and the fanatics of a decapitated god, all in the hope of saving Eando Kline, one of the greatest explorers the world has ever known. But even if they manage to free Eando, can the PCs escape from their captors, the legions of snake-men fangs?