Your job is to gather incriminating evidence against the leaders ofthe Iron Throne. Go to the Iron Throne (Area-C, #60), and work youway to the 5th floor of the building. There are some scrolls to befoundin the basement and in the Library on the fourth floor. Along theway you will encounter some NPC's who may give you some information aboutthe Leaders on the 5th floor. The guards on each floor can eitherbe talked into letting you pass, bribed, or fought.
The battle starts as soon as you enter the 5th floor. I foundthat going up by the stairs on the right was a better tactic as the leadersseem to be spread out more towards the left stairs. Since the battlestarts as soon as you get to the top of the stairs (you don't have timeto look around), it was hard to tell if there were any friendlies in thearea. Emissary Tar appears to be there, but I believe she is alsoa doppelganger. From the stairs you will have to battle the leadersGardush, Ali, Neaman, Dryab, and Aasim and a couple doppelgangers.I didn't use area weapons for fear of hurting friendlies (actually, therewere not any friendlies on this floor), so I stuck with ranged weapons,Animate Dead spell, Wand of Monsters, Wand of Heavens (a great graphic),and the Purge Invisible spell. For ranged weapons I used Arrows ofAcid and Bullets +2.
As soon as the battle starts, some leaders cast Dimension Door and somecast Invisibility. So be ready with the Purge Invisibility spell(I had to use it twice before the battle was over). I was also preparedto use Protection from Magic potions, but never needed them. Branwen'sSkeletons (from the Animate Dead spell) and War Dogs from my mages Wandof Monsters did a good job of keeping the Leaders busy. (Ever noticehow these summoned monsters are able to attack the monsters/charactersthat are invisible to you - neat huh!) Things got a little confused whenone of the Leaders cast Confusion, which caused half of my War Dogs toattack my Skeletons and some party members. But in the end all theLeaders went down with very little damage to my party. After the battleI avoided my confused War Dogs until they were unsummoned, then commencedto search the bodies. Be sure to search as there are some good thingsto pick up (e.g., Ring of Free Action, Halberd +2, Wand of Heavens, andmore).
After bashing the Leaders, search the rest of the 5th floor. Ina nearby room you will find Thaldorn who will immediately attack.Missile weapons took him out quickly. Thaldorn carries a Short Sword+1 and Studded Leather +1 (probably not of much use to you at this stageof the adventure). Continue searching and be sure to check out thedesk in the back room. This contains two letters, one from Tuth toReiltar and the other from Sarevok to Reiltar. ****You need to findthese letters to complete the chapter****.
After picking up the two letters, and anything else you want, go backto the Flaming Fist HQ and talk to Duke Eltan (don't bother to look forScar as he disappeared as soon as you took this quest from the Duke).At this point you can tell the Duke you have other business in the cityand will return (so you can do some more city adventuring, but rememberthat Scar is now murdered and you may be pursued by Flaming Fist Enforcers- not tested!). Or, you can tell the Duke that your evidence showsthat the answers he needs can only now be found in Candlekeep. Ifyou tell him this, he will tell you to go to Candlekeep to investigatefurther, give you $2000 and a book ("History of Nether Scrolls") to useto gain entry to Candlekeep, and teleport you to the Candlekeep map sector.
I have been emailed that as soon as Scar disappears, you are blamedfor his murder and your life in the city streets is hectic as you are pursuedby Flaming Fist Enforcers. I have not tested this, so cannot commenton it.
Since Duke Eltan teleports you to Candlekeep on completion of his quest,you should perhaps visit a shop or two, prior to that last visit to theDuke, to sell items and buy supplies.
UPDATE: Now that I have completed Chapter 6, I can say that itis something you do in Chapter 6 that causes the Flaming Fist Enforcersto pursue you when you get back to BG in Chapter 7. You are NOT blamedfor the death of Scar when you do the Duke Eltan quest in Chapter 5.