From the first page of the PDF:
Shadows grow long in the free city of Urmlaspyr. The city calls for adventurers, as the rising darkness overwhelms the capabilities of the city guard. A noble’s manor has been overtaken by shadowy undead. Can you reach the source of the haunting and stop it before it spreads throughout the city? A Living Forgotten Realms adventure for characters of the Heroic tier (levels 1-10).
This adventure is part of Chapter 1 of the Desolation series. Chapter 1 includes four Heroic tier adventures leading up to the conclusion in CORE5-1. The other three parts (in addition to this adventure) are SPEC4-5, CORE4-3, and CORE4-4. You can play these four adventures in any order, but you should try to play them with the same character, and you should try to play all four parts before you play CORE5-1. The Desolation series also includes Paragon tier adventures (starting with SPEC4-6). It is not expected that a player can follow both tracks with the same PC.