Welp, time for the second entry in what I hope will be a series about the new quests added to Baldur's Gate II: Shadows of Amn by installing the mod "Unfinished Business". As long as the admins don't object, and I keep finding them, I'll keep doing them.
Unfinished Business Quest #2: The Search for Boo
To trigger this quest, one must have Unfinished Business installed, have Minsc in the party, and leave the Docks district in Athkatla. Other requirements are unknown at this point.
Upon arriving in the new area, Minsc will have a sudden freak out as he discovers that Boo has gone missing. If Gorion's Ward does not react in too harsh a manner (which will cause Minsc to leave the game permanently), Minsc will plead to be taken back to the Docks, which is where he last saw Boo.
Since the loss of Boo has a demoralising effect upon Minsc that drops his Strength from its former mighty 18/93 down to 10, it's in the player's best interest to tackle this quest quickly.
Head to the Athkatla Docks and, from there, head to the Sea Bounty Tavern. Minsc will identify a boy, "Billy", as someone he observed looking at Boo the last time the party went through, and you will chase Billy into the rooms. Billy flees to the protection of some men, who will ask what the matter is; if the party is not diplomatic, you will trigger a fight.
Whilst Billy demands 50000 gold pieces for Boo, Gorion's Ward can instead appeal to his protector, Vivick, to control him. Whilst the player can pay him 50 or 500 gold pieces, the easiest way is to point out that Minsc is a hugely strong and mentally unhinged berserker. Recognizing that it's probably best to give the crazy thug back his precious pet before he goes into a killing rage, Vivick makes Billy explain what he did.
Billy explains he sold Boo to a halfling petshop owner named Smethy, and leads the party there before running off. Smethy calmly explains he bought Boo from Billy for 1 gold piece, but then sold him for 50 gold pieces to a young girl from the Government district named Eleana. If the party is polite, he teleports them there directly so they can see about retrieving Boo.
Eleanya can be found at the lone fountain, just south-west of the Government Park square to which Smethy teleports the party. If the party insults her too grievously, or threatens her with violence, she blasts Gorion's Ward with a five-bolt Magic Missile spell and then runs off, letting four De'Lyl guards try and "discipline" the party for her. When the party slays them, she will surrender and, chiding the party about killing four men for the sake of a hamster, return Boo, giving the party 15000 EXP. Alternatively, a diplomatic party can agree to play Eleanya's riddling game for ownership of Boo.
For the first riddle, the answer is "Noise", though she will also accept "A Wheel" or "Passengers".
For the second riddle, the answer is "Cabbage".
For the third riddle, the answer is a "Laeral's Tear" or "You need no gem".
Get only one riddle correct and the party will be rewarded with 10000 EXP. Plus the return of Boo.
Get at least two riddles correct and the party will be rewarded with 15000 EXP and the Jade Hound Figurine, which can summon an Astral Hound to fight at the party's side once per day. Plus the return of Boo.
Get all three correct, and the party will be rewarded with 20000 EXP and Minsc will gain the ability "Boolets", which lets him summon a hamster once per day. Plus the return of Boo.
Get all answers wrong, and you get no EXP, but Boo is returned to you.
Once the noblewoman leaves, one way or the other, two Cowled Enforcers will teleport in and thank you for getting rid of the arrogant wench. They will also ask if you have a magic license; if not, they will grant you one, otherwise they give you 1000 gold pieces.
Unfinished Business Revision #1: Ungar Hilldark's Stolen Illithium
In vanilla Baldur's Gate II, Ungar Hilldark simply sends the player directly to confront Neb once they approach him. With Unfinished Business, the duergar has a request first: he asks you to go to the Temple Ruins and see if you can find out what happened to his brother, Gorje. Rescue the trapped duergar from the shadows, and they will tell you about Neb, whereupon the quest plays out like normal.