From the first page of the PDF:
For years the tenuous peace between Netheril and Cormyr held. For years the city of Urmlaspyr, last remnant of free Sembia, cursed to be shrouded in darkness since decades, lay in between. Now something stirs in the darkest places of the city, something dangerous, something vile, something that will disrupt the fragile balance. Will the city fall to the darkness well known, or something else? A Living Forgotten Realms adventure for characters of the Heroic tier (levels 1-10). This adventure is chapter one and the Heroic tier introduction, to the Desolation series. The series has both Heroic and Paragon tier adventures and it is not expected that a player can play both tracks with the same PC.