From the front of the book:
Following a secret meeting with the high priests of Selûne, a recently obtained artifact, the Last Grasp of Shadowbane, has vanished. With its hunger to conquer shadow creatures, the weapon could forever change the balance of power in Netheril. Someone is needed to locate the artifact and ensure that it is used for the purpose it was intended. A Living Forgotten Realms adventure set in Netheril for characters of the Paragon tier (levels 11-20). This adventure is the first part of the Sand and Shadows Major Quest, which continues in NETH3-2 and concludes in NETH3-3. We strongly recommend that you play these three adventures in order, with the same character, if at all possible.