Descent Into the Depths of the Earth is an adventure module for the Dungeons & Dragons (D&D) 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 (AD&D) 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. Plot summary The plot of the original modules Descent Into the Depths of the Earth and Shrine of the Kuo-Toa places a party of player characters (PCs) on the trail of the drow priestess Eclavdra through the Underdark, a vast subterranean network of interconnected caverns and tunnels, battling various creatures on their journey. In the last module in the preceding G-series, Hall of the Fire Giant King, the PCs were supposed to have discovered that the drow had instigated the alliance between the races of giants and their attacks on neighboring humans. The drow that survived the party's incursion have fled into tunnels leading deep into the earth. The adventurers will have arrived at the bottom of the dungeon below the cave-castle of King Snurre. In D1 Descent Into the Depths of the Earth, the PCs seek the home of the drow by traveling through an underground world of caves and passages. In the tunnels, the adventurers first fight a tough drow patrol, and the next major fight is with a raiding party of mind flayers and wererats, who have halted their patrol long enough to torture their drow prisoner. The characters also find a grand cavern containing drow soldiers, purple worms, a lich, a clutch of undead, a giant slug, sphinxes, trolls, bugbears, troglodytes, wyverns, and fungi. D2 Shrine of the Kuo-Toa picks up with the party continuing to pursue the drow. The party encounters a kuo-toan rogue monitor who helps