This is the third book in Larsson's "Millennium" trilogy, the others being The girl with the dragon tattoo and The girl who played with fire. While there is something of a gap between the first book and the second, this one carried on right from where the second one leaves off, so if you've read the second book, don't wait too long before reading this one, because it is in effect one long book in two volumes. Leaving it too long might mean that you forget some important elements of the plot.

I also think that this one is by far the best of the three.

I won't describe it, because saying too much would probably be a spoiler for the second book if you haven't read it. I didn't learn much from it, and its nothing profound, just a good story, well told. It differs from the preceding one in that there's more police action, and a bit of courtroom drama thrown in.