From the first page of the PDF:
No one knows why the aboleths of Xxiphu take so many prisoners. Their motives and minds are as alien and incomprehensible as the Far Realm itself. Their flying city appears seemingly at random, striking at locations all around the Sea of Fallen Stars and vanishing as quickly as it appeared. The luckier captives are simply killed outright. Those less fortunate are subjected to horrifying experiments, transforming their bodies and minds in ways that not even the Plaguescarred would recognize. But this time the Abolethic Sovereignty has gone too far. It's time to take the fight to Xxiphu. It's time to crack open the writhing obelisk.
A Living Forgotten Realms Special adventure set in the Sea of Fallen Stars for characters of the Paragon tier (levels 11- 20). This adventure will be of particular interest to characters who played CORE1-11 Drawing a Blank, or who have
previously encountered agents of the Abolethic Sovereignty. This adventure takes place at the same time in-game as SPEC4-1 Cerulean Dreams, so a character that played SPEC4-1 may not later participate in SPEC4-2.