Here is the first part of finding the Underworld and Larad.
Note: you'll face some very difficult monsters in the Underworld. Some of the quest rewards you gain from doing the mini-quests in Etum are priceless. One is the Jewel of Well Being (Mass Healing 1x per day) I usually carry about 8 of them. They work like a area of mass destruction to undead. While undead can save out of it, Use another and you'll tag them. It takes them to near death so one hit will kill them. You should have either items or spells to protect against Death Magic. You will face demiliches, Dracoliches and other powerful undead. Once on Taer Prison Isle, none of your teleport items will work so stock up before you start.
From the Taer Portal stone, head south, take the middle exit and stay on the east(left) side of the map, keep moving south through several areas exit at Taer Oasis. head east to Taer prison dock. The boat there only takes you back to Etum. Take the area transition at the end of the pier to Taer Prison Isle.
Enter the Prison building in front of you, find your way around the hallway you'll see a central area with two rooms with a stairway leading down. This takes you down to the Prison complex proper. Here where it gets tricky. What you're looking for is a stone grate that leads down. There is an area script that places that stone grate in one of 8 different locations, if you go back up the stairs and come back down it can remain in the same place or appear in one of the other 7. If you hit tab or mouse over it , it will highlight blue. Sometimes it is in the warehouse area, you have to go up the stairs, exit the prison and go up and over to get to the warehouse...then it can have moved again...In the large area in upper left of the map. you'll find a map in a barrel which helps finding your way around.Just keep going up and down the stairs and keep looking for the grate.
Once you find your way down to the Catacombs, fight or sneak your way past Geletanous Cubes and Cursed Undead to a portal that takes you to the Upper level of the Underworld.
You can rest where you arrive in the Underworld in the lower left corner of the entry area. In this area you'll find Azer, Larad Soldiers\guards Demi-liches, Harpies, Admantium Golems, Bodaks and Larad's underling Vertigen Domax. He is undead so use a jewel on him. He hold the key to the underworld, plus the excellent longsword 'The Sword of the Storm" A +10 weapon that does electrical damage and has other useful effects. Find the stairs down in the upper left area of the map...Now you ready for level 2 of the Underworld.
To be continued in Part 2.
-Alaric
An edit note; I forgot to mention that Domax also can appear in one of 8 locations on this level. Sometimes near the demi-liches...sometimes in a hallway or side rooms. Besides protection from death magic you should be protected from fear. The cloak you gain from the werewolf mini-quest, or dragon slippers work.