Descent into the Depths of the Earth

Blurb

Descent Into the Depths of the Earth is an adventure module for the Dungeons & Dragons fantasy roleplaying game coded D1–2. It was written by Gary Gygax, and combines two previously published modules from 1978, the original Descent into the Depths of the Earth and Shrine of the Kuo-Toa. A sequel to the first two modules, Vault of the Drow, was also published in 1978. All of these D-series modules were produced for use with the 1st edition Advanced Dungeons & Dragons rules.
The D-series itself is part of a larger overall campaign of adventures set in the World of Greyhawk campaign setting. The overall campaign begins with the three modules in the Against the Giants series, continues through the D-series, and concludes with module Q1 Queen of the Demonweb Pits. The latter segments of the campaign, including the D-series and module Q1, are set in a vast network of caverns and tunnels called the Underdark.