From the back cover:
Evil Never Dies
Years ago, brave heroes put the denizens of the Temple of Elemental Evil to the sword. Now, dark forces whisper again in the shadows of the once-deserted temple - forces far more insidious and dangerous than any sane person could dream. Evil has risen again to threaten the village of Hommlet.
Characters battle the power of darkness in Hommlet and beyond, forging their way through hundreds of dire encounters before reaching the fiery finale. Designed as the backbone of a full campaign, Return to the Temple of Elemental Evil takes characters from 4th level to as high as 14th level.
This deluxe adventure builds on the groundwork of the original Temple of Elemental Evil (published in 1985), as well as other classic adventures. However, none of those products are necessary to enjoy this one. To use this adventure, a Dungeon Master also needs the Player's Handbook, the Dungeon Master's Guide, and the Monster Manual.
Expanded by;
Caves of Ancient Secrets