From the front page of the PDF:
You had already entered Many-Arrows to steal a relic from a small temple when you received a desperate message: slow down the orc horde before it joins forces with Netheril to invade Cormyr. How are a few adventurers supposed to stop the throngs of Obould's orcs? It won’t be easy, but you could become a legend. A Living Forgotten Realms adventure set in the Kingdom of Many-Arrows for characters of the Heroic tier (levels 1-10).
This adventure takes place before ADCP6-1 The End and the Beginning, and its outcome has an impact on the course of the battle. This is the Heroic tier finale of the Desolation series.