In the world of Toril, beneath the land of Faerun exists a vast underground network of caves, old mines and catacombs. This underground realm is known as The Underdark. It is here, miles from the surface, that a group of slaves is currently working on a tunnel for their Illithid masters. Bound by magic this group of many different races have no choice but to serve, and are working effectively together. Suddenly, for some unknown reason the spell of the foremost slave is broken. Choosing death over recapture, the mighty minotaur brings down the mine-shaft upon himself, the other slaves and their masters. The floor cracks up beneath them, and some of them fall down. Halfway down, the spells of the falling slaves are also broken, leaving them to be free willed. For most of them, this is a short-lived ordeal, but for a lucky few they survive the fall and the impact with the water underneath.
Most of the miners have now been crushed by the rocks up ahead, or underneath those sinking down into the water below, but somehow four have survived. Two drow, Ilivarra and Kelnazz, a dwarf from the highest parts of the underdark, Dorin, and a young gloamling sorcerer, Verran.
Deciding to work together rather than facing the merciless underdark alone, they start searching for some way out. The gloamling finds a tunnel underneath the waters, and the dwarf is the first to take the initiative and starts walking along the bottom as he’s held down by his armour.
After chasing away a hungry dire-rat, the party continues on, encountering a large chamber with webbing along the ceiling and some of the walls. Carefully moving through the room, a huge spider attacks them as they are leaving, having dropped their guard a bit too much. After a swift battle, Verran have been severely injured, but the spider is defeated. The others manage to patch him up, and after stopping for a while to rest, he is strong enough to keep on.
As they come to the first junction they encounter, they decide to keep moving upwards, a choice they repeat as they a while later arrive at a stairway stretching both ways as far as they can see. When they finally reach the top of the stairs, they find a dire-rat – most likely the one Dorin chased away – lying dead in the middle of the room. After a quick inspection, they find it to have been killed by a blunt blow. Searching the floor for tracks, Ilivarra finds traces of some number of bipedal creatures passing by here within not so long. Studying the exits, they choose to walk down one of the ones showing lesser traces of traffic.
It leads them to a large room filled with, among other tings, crates of uncut emeralds and a pair of pillars close to the middle of the room. As they hear rushing footsteps, Ilivarra accidentally walks between the two pillars, and finds that there is a portal there, taking here to another cave. She quickly returns to inform the others as a small group of quaggoths attack from the way they came. They fight them off, and then the dwarf yells for them to retreat through the portal.
The party complies, and they find themselves in a dark cave stretching forward as far as they can see with no idea where they are or what lies ahead.