From the back cover:
A new age dawns...an age of terror!
They are close. I can feel them even stronger, now. It won't be long before the Masters come again. I have waited for them, waited for their return. Once they extinguish the Light, the true Dawn can begin.
The illithids once ruled a mighty empire that stretched across many worlds. These foul creatures enslaved or destroyed whole races in their quest for ultimate power - until a rebellion spread like fire on dry plains. The mind flayer empire toppled, and the multiverse was freed from eternal servitude.
Now, a hundred suns burn toward extinction, their light stolen by the flayers to reinvent the past. If the PCs do not stop the new dawn, the Dawn of the Overmind, the illithids will rule once again! Following the clues left by their benefactor, the adventurers journey over a vast world of ancient ruins. Buried deeply within these ruins lies an artifact of ancient illithid manufacture. This item is all that stand between the illithids and their nefarious goal: complete and utter domination.
Dawn of the Overmind is the third adventure in a trilogy (originating with A Darkness Gathering and continuing in Masters of Eternal Night). It can be played alone or linked with the other two parts of the trilogy to form an epic-length adventure. The illithid trilogy supports The Illithiad, a MONSTROUS ARCANA, supplement that contains invaluable information on every facet of illithid life, psychology, technology, and ability.