Baldur's Gate 1 - Chapter 6 Walkthrough
This chapter begins with us standing outside the same town our journey first began in, Candlekeep. Speak with the Keeper of the Portal outside Candlekeep and give him the book that Duke Eltan gave you, this will gain you entry into town. There isn't much to do in Candlekeep during our return, head into the library in the center of town and start exploring/going up the stairs.
We have 2 main goals inside the Candlekeep Library; the first of which is to speak with Rieltar the leader of the Iron Throne on the 3rd floor and the second is to get arrested. Depending on your actions where and how you will be arrested changes slightly. If you decide to kill Rieltar you will be arrested immediately after leaving the 3rd floor. If you don't kill Rieltar you'll be arrested when you reach the 6th floor. Those of you who avoid speaking with Koveras and avoid getting arrested on the 6th floor will get arrested when you try to leave the Candlekeep Library.
Usually the best path to take is explore floors 1 - 5 then return to Rieltar and kill him. This way you can collect most of the available loot throughout the library as well as the loot on Rieltar and his comrades.
Second Floor: Koveras will bother you here and give you Koveras's Ring of Protection +1 if you agree to accept it. One thing to note is speaking with Koveras will flag you for being arrested when you reach level 6.
Fourth Floor: Shistal is found here who is a Doppleganger that you can defeat for 4000 EXP
Fifth Floor: Gorion's Bedroom can be found on this floor, inside is a Letter which gives you a lot of backstory. Your father is Bhaal, lord of Murder and Sarevok is your brother. You can also find a Cloak of Protection +1 on this floor.
Sixth Floor: Tethtoril's Room is on this floor and you'll find a Ring of Protection +1 inside a chest in his room. Aside from this there are numerous Potions, Scrolls and piles of Gold you can find throughout the floor.
After getting arrested you will be sent to jail and visited by 2 people during a cinematic of sorts. The second person to visit you will be Tethtoril and he will assist you in escaping by teleporting you and your party into the Candlekeep Catacombs; this is where you will regain control of your characters. Be sure to search the room you're teleported into as there will be many scrolls here that you can teach to your casters.
On the first floor of the Candlekeep Catacombs you'll also find a ton of good loot for your party, I have each loot location marked on my screen shot below. Hopefully you have a Thief in your party since you'll need them to open all the tombs/containers with loot in them.
On the second floor of the catacombs you will encounter a lot of Dopplegangers. You will also run into Arkanis and Deder who are not Dopplegangers and will offer to assist you in combat while you're on this floor. It's up to you if you'd like to accept their help or not, I recommend you do as the extra hands makes things easier.
It doesn't matter what you say to Elminster, Gorion and Tethtoril, they will lead you into an ambush if you trust them otherwise you'll fight them where they stand. As far as loot goes there isn't much for you to collect on this floor, continue to the northern portion of the map and down to the 3rd floor.
When you arrive on the 3rd floor go south immediately and you will encounter a group of enemies that work for Sarevok. Take out Prat and Sakul first since they are the mages then deal with the others. You'll get a lot of loot for this fight including a Throwing Axe +2. Our next major fight is in the southern portion of level 3 where you will fight 2 Greater Basilisks. For those of you playing on a difficulty where characters can be turned to stone I recommend you use something like Potion of Mirrored Eyes, Protection from Petrification (Spell), or Potion of Invulnerability if the previous 2 aren't available.
After taking out the 2 Greater Basilisks you'll be confronted by Diarmid who will reveal some details to you if you play along and say you're Prat. Otherwise you can fight him for a measly 240EXP and some magical arrows. To complete this dungeon simply exit the same way Diarmid came in. You'll find yourself outside Candlekeep and with that we're officially done with Chapter 6!