From the introduction:
The Hour is Ripe for Conflict!
The Cults of Elemental Evil had wrought incredible destruction on the city of Mulmaster, and in its hour of need, the City of Danger received aid from an unlikely ally – the Mageocracy of Thay. Now, with Mulmaster moving ever closer into Thay’s orbit, strife is brewing within the Factions as some call for action against the Red Wizards.
This three-hour Epic Adventure was published in four tiered implementations, each optimized for a specific APL.