Save Jaheira From Baron Ployer's Curse - BG2 Side Quest
The Save Jaheira from Baron Ployer side quest begins the first time you enter the Sea's Bounty Tavern in the Dock's District with Jaheira in your party. Baron Ployer will immediately begin dialogue with your party and during that dialogue Jaheira will be cursed and this quest will start.
Warning: If it wasn't already obvious to you, this quest is timed. Each day that passes will cause Jaheira to get weaker and weaker. Also, if she dies while the curse is active and you try to resurrect her she'll die immediately again. For this reason it's highly recommended you focus completely on this quest once it begins.
You will be given 3 leads to follow from Jaheira after she is cursed but this whole part of the quest is optional. If you want the extra EXP I would recommend visiting Corneil in the Council of the Six building in the Government District. He won't have any useful information but when you leave the Council of the Six building you'll be approached by Terrence whom you can pay 1000 or 500G to cut ties with Baron Ployer (doing this will mean Terrence will not back up Ployer when you attack him). You'll earn a total of 10k EXP for paying Terrence.
For those of you who aren't interested in the measly amount of EXP and you just want to complete the quest as fast as possible... Head over to the Slums District and visit the Derelict House in the northern portion of the map. This is where Baron Ployer can be found.
Upon entering you'll have some brief dialogue with Ployer after which he'll summon some mages to help him and the battle will commence. If you paid Terrence earlier then Baron Ployer won't get any back up and you'll be given an alternative option of convincing Ployer to stand down. This is an alternative way to complete the quest, convincing Ployer to stand down will net you 21k EXP as a reward. Alternatively, if you paid Terrence to kill Ployer then you'll get no EXP.
In my opinion the best available route is to avoid Terrence altogether that way you can take out Ployer and all of his buddies. They drop a lot of magical items and they're all worth a decent amount of EXP anyway. Plus, it's way easier to go straight to the Derelict House and kill Ployer once you begin the quest.