This expansion was released in 1999, but doesn’t add to the game’s main storyline, unlike what Throne of Bhaal does for Baldur’s Gate II. Instead, you get several new sidequests, all originating in the small village of Ulgoth’s Beard, located to the north of Baldur’s Gate. There are four quests in total, two of which are very lengthy. The first quest involves a mage forcibly teleporting your party to a prison island to retrieve his cloak. The second one involves a man with a strange accent asking your party to travel to a remote island inhabited by descendants of the shipwrecked crew of Balduran himself (N.B. the founder of Baldur’s Gate), as well as a pack of werewolves. The third quest takes your party to Durlag’s Tower, a huge stronghold with a scary reputation. It was originally built by a dwarven lord and is rumoured to contain treasure. However, the entire dwarven clan got massacred by doppelgangers, and Durlag trapped the place from cellar to attic in an attempt to defend himself. Moreover, there appears to be a much more sinister presence on the premises as well. Your party receives two requests to go there: one from a woman whose son foolishly joined a party of adventurers set on exploring the place and another one from a man seeking a dagger. The fourth quest involves said dagger and a demon-worshipping cult.
The highlight of the expansion is, quite clearly, Durlag’s Tower. It’s longer and more difficult than any dungeon in the main game, and your party ends up facing a pretty nasty boss. If you enjoy a challenge, then this will be right up your street, with some very nice loot as a reward. I personally find it a bit too long and too tedious, but I have to say that the atmosphere is effectively eerie, especially in the lower levels, where you learn how exactly the attack on Durlag’s clan happened, with the help of creepy little rhymes strewn about the place by Durlag himself.
The Balduran’s Island quest bothers me a bit, because it features a glaring continuity mistake. It takes your party weeks to reach the island, but they either take mere days to come back, somehow, or the game lies to you about the fact that you need to return from the island as quickly as possible because your time is limited. The writers probably forgot all about how long the travelling time was supposed to be when they finished writing the quest. Apart from that though, it’s quite original, even though you can guess what’s going on pretty quickly.
Apart from these sidequests, the expansion also introduces some minor gameplay modifications. First of all, the experience cap is raised, so that you can take full advantage of the new enemies the quests introduce. The interface is slightly improved, including the automatic stacking of identical items–you had to do it manually in the vanilla game–and a visual indication of items that require identification. There are also some slight adjustments to Thieves’ abilities–they now need to actually position themselves for backstabs–, and any character can now effectively dodge a spell by moving out of its area of effect, rather than solely relying on Saving Throws.
All in all, this is a worthwhile addition to the game, despite not having any actual bearing on the storyline.