Zered Tou (named because it borders the Great Dismal Delve) is a vast underground city with an obscenely dense population. It lies in a hollowed-out cavern in the Elemental Plane of Earth, but its inhabitants are from elsewhere.

The rulers of Zered Tou are hobgoblins, a pathologically cruel and tyrannical breed exiled from their native Prime, which they call simply "The World Under the Mountain."

The notable features of the World Under the Mountain are as follows:

1. There is only one mountain in the whole world. It starts at sea level and extends beyond the sun and the moon. Secret caverns within it lead to the outer planes.

2. Only dwarves are permitted within the Mountain, and thus only dwarves can intercede between mortals and the gods of the sky, who rule the universe. Dwarves thus control all the temples to the gods of air. If they abuse their power, no one has caught on. Dwarves themselves have a more jaded, planar view of religion - they respect the Powers, but they respect the soul and its potential more. Alone of the races under the Mountain, they understand why mortal belief is so important to the gods.

3. The rest of the land is a low-lying chain of islands, and a sea that stretches to the horizon where it touches the dome of the sky. The climate ranges from tropical to a very warm temperate.

4. The primary races of the world are humans, orcs, and gnomes. Elves are nearly extinct, having lost their war with the gnomes. The last remaining elves live in the orcish kingdoms; the orc-king would love to see the gnomes dead and the elves returned to their former power (and in the orcs' debt), but the reclusive orcs are reluctant to go to war. Orcs are civilized and ancient, and respected for their knowledge of written magic (especially necromancy, and the binding of unfriendly spirits). Orcs worship gods of the night sky.

The only rivals orcs have in magical skill are the Red Gnomes, who love magic of all kinds so much that they scarcely think of anything else. The Black Gnomes, who were created by the Red Gnomes as part of their ancient war against the goblins, take advantage of this affinity in their equal obsession with conquest. With the goblins gone, the Black Gnomes now wish to defeat everyone else. Gnomes revere the god of the sun as the source of magic.

Humans have two main civilizations: in the north, humans live in adobe cities and worship the gods of the day-sky and rain. Birds and feathers are considered sacred. They have good roads and canals but do not use the wheel. The nations of the northern civilization are ruled by princes, who control regional barons and lords. In the south, humans live in loose tribes who live in fear of a terrible mother goddess who only married female warriors can intercede with. They contend against lamias and nagas.

Halflings are primitive and filthy, and known child-thieves. Their patron god is a terrible demon that resembles an aborted fetus. Only goblins can stand halflings, and only halflings can stand goblins. Goblins are very fascist and cruel, allowing their citizens very little personal freedom and no privacy. Their slaves are treated much like citizens, except they get no pay. Once, they worshipped all the elements, but their civilization offended the gods of the sky, who threatened to flood their cities, and the gods of flame, who threatened to burn them. The other races, especially the elves and their then-allies, the gnomes, drove them from their lands. The gods of the earth offered them refuge.

Zared Tou is a typical crowded goblin city. Its main enterprise is using slaves to excavate one of the Anchors of the World. Without the anchors, the world would drift into the sky. To make sure that doesn't happen, the powers of earth want the

anchors in their own keeping. Because they are forbidden from excavating the Anchors themselves, they require mortal servants. And their mortal servants require a continuous flow of slaves.

Each goblin city is built around one of the Anchors. There are four in all.

4. Only the orcs have the shipbuilding technology needed to cross the sea. They have colonies in distant islands where strange races dwell: gnolls, minotaurs, medusae, giants, tako, tabaxi. From these exotic peoples, orcish explorers have heard tales of other mountains, on top of which banished elder pantheons dwell in their private universes.

5. The gods of air and heaven rule the world through their servants (devas, djinn, couatl, shedu, asuras, lillendi, air elementals, ki-rin, archons, etc.), and directly control the activities of the gods of fire and water on this world. Only the gods of earth are free, and feel rather cornered.

1. The adventurers, while passing through the Plane of Earth, are attacked by bloodthirsty halflings who wish to enslave them and sell them to the goblins. If they defeat the slavers, they may be curious enough to explore further.

2. A sage living in Automata has heard of the Anchors of the World, and hires an adventuring party to investigate them. She tells them that the colony of winged elves in the cavern called Aviary would be willing to help them explore in secret.

3. The powers of Fire and Water wish to get hold of the Anchors for themselves, in the hope that they can move the World Under the Mountain closer to their own realms. Because none of the races under the Mountain worship fire and water gods directly, those elemental powers who are interested in this world must find planewalking mortals to act as their instruments. Through their servants (which vary: efreet, azers, tritons, nereids, baatezu, and marid are some suggestions) they find small bands of recruits that the gods of sky are unlikely to notice. A representative makes a pitch similar to that of the sage in hook 2, adding that servants of Sky - like the winged elves - must not know their purpose there.

1. Zered Tou is in the midst of turmoil. The old Lord of Discipline is dead, poisoned by his daughter. She is the logical successor (she would rule as Princess of Discipline; although a female may not be Lord, princesses have ruled off and on for seven hundred years, since the first Princess of Discipline had all her brothers hung). However, a group favoring Slavemaster Erzik, who may be the old lord's bastard, is trying to discredit her. Discovering humans - worse yet, elves, or even dwarves - running free in her private chambers would do the trick. They may try to lead some that way.

2. The goblins keep mazes filled with elemental monsters. These wind around the city's public passages, and are often the easiest way to sneak around - if the monsters don't kill you. Sewage lines (leading to a rancid lake, which may have a conduit to the Plane of Ooze) are a third thread. Completely safe secret passages are a fourth. Figuring out which door leads to which at any one point is tricky.

3. A mixed group of Black Gnome warriors and Red Gnome sorcerers are attempting a raid on Zared Tou. They have no problems with killing those who get in their way, or with killing elves of any kind. However, they may be willing to share their escape route if properly motivated.

4. The dao are impatient with the goblins' progress. Several dao are meeting with the princess, demanding more efficient slave use or the dao will step in to command the goblins directly. If the princess were to lose her bid for the throne, the dao would also take over - and the next time the PCs see her, she may be working with Erzik's rebel forces.

5. Some of the mazes have small groups of escaped slaves. Many of the slaves are from the World Under the Mountain (dwarves, humans, and orcs), but some are elemental-kin bought from the dao. Many of them have very extensive maps of the area, and might be willing to find them for the PCs in exchange for help making it out.

In any case, the main thing the PCs are expected to do is go in, make or bargain for maps, and get out. The easiest way "out" might be the gnome's path to the World Under the Mountain, or it might be the conduit to the Plane of Ooze (where the PCs might find shelter in the court of Bwimb, in a town of friendly plane-lost gnomes, in a community of scavengers living off Sigil's debris, or in a cyst where an insane-but-perhaps-not-homocidal wizard has been imprisoned by rivals who now control something important (like the Planar Trade Consortium, or the Shadows of the Spire sect, or Rigus)). The PCs probably aren't so lucky that they can use the same way they came in.

If the PCs learn of the mountains of the elder gods (from enslaved orcish sailors), they may be asked to journey to them in the future and ask them if they would help the gods of fire and water in unseating the gods of the sky.

They might be asked to lead a second expedition to Zared Tou, by the sage in Automata or even by the expatriate princess.

They may be asked to aid creatures from the Plane of Ooze in expanding their realm enough to steal the anchor.

Perhaps they would like to aid the elves of Aviary against the dao or angry goblins instead, by helping organize an alliance with other races of Earth (like the shad, or the pech), or by finding an artifact that could hide them (What else can it do? Does it manipulate earth or shadow? Are there drawbacks? Can it also hide or even free an Anchor of the World?).

Maybe they meet other groups with problems or rewards.