Baldur's Gate: Dark Alliance II is just like the first one, but there's more of it.
That's it; that's all; you can all go home, or to the store, according to your individual preference. There isn't a hell of a lot else to say.

Dark Alliance II begins about thirty seconds after the end of the first game, after the fall of the Oynx Tower. The three heroes of the original game step through a magical portal. They wind up in a dark forest somewhere, surrounded by shadow knights, with what is clearly a very bad man ominously lurking in front of them. He thanks them; the knights close in.