The Unknown Tunnels are hidden and do not appear on the map. Rather, they are keyed by a random encounter on the world map (in Maj'Eyal). You must be at least level 18 for this encounter to occur. The encounter text is:
- You find a hidden trap door, and hear cries for help from within...
Choosing to enter will put you on level 1 of the zone. The top level is a darkened maze of single-wide corridors, with no exit back to the surface, and only a single (randomly placed) exit leading downward.
The second level has a fixed layout with some rectangular rooms on a lighted, open level, with some NPCs (see below). You will find a merchant (nonhostile), the Assassin Lord, and assorted rogue-type henchmen. This is the body of the Trapped! quest.
Of note is the presence of summoning traps, which when stepped on surrounds you with thieves. This can pose a significant danger for an unaware character, particularly if lightly armored or susceptible to sudden perforation.