The Watcher of Ages

Publisher blurb:

Hundreds of years ago a once mighty fortress in Cheliax sank into the earth and was forever destroyed. You are sent there to catalog the ruins, known as the Collapsed Halls, and to find the rumored hidden tomb of an Osiriani concubine. After clearing the ruins of hideous beasts, you explore deeper into the ruins than anyone before you and uncover a malevolent intelligence that has watched Golarion for more than 5,000 years. Worse, he knows you're coming.

The Watcher of Ages is part 2 of the Echoes of the Everwar series. Parts 1, 2, and 3 can be played in any order and part 4 must be played last. Look for part 3, Pathfinder Society Scenario #44: Terror at Whistledown, in February 2010.