Deep below the anarchic city of Kaer Maga, someone—or something—has begun stealing corpses from the city’s most prestigious tomb, the Godsmouth Ossuary. Fearing the worst, the clerics of Pharasma in charge of maintaining the crypts quietly call for aid, not wanting to risk their own members in combating whatever horrors may have crept in from the tunnels and hidden chambers of the legendary Undercity. Beneath the infamous crypt lies a temple from an ancient empire devoted to sin, and a former Pharasmin cleric whose weathered his goddess’s wrath to create an army of undead minions, their dead flesh standing ready to support his heretical plans.