It's kind of hard to give a summary of this one without giving away The Girl Who Played with Fire. Hornets' Nest literally picks up right where it left off, so I'll give you a basic overview of what's happening in this book. Basically, Lisbeth has gotten herself into a lot of trouble, and Blomkvist has stumbled into a bigger mess than he actually thought. I won't say much more than that, because too much more will give it away. But hopefully, I sparked your interest. If you want to know more about what the whole trilogy is about, visit my previous posts on the matter, "Slow Beginnings" and "A Thrilling Read." They contain excellent summaries to get you started. :)
The thing that I liked the most about this book was the way Larsson wove different conspiracies throughout the book. The reader really has to pay attention to who's speaking at that part in the book, because it switches points of view a lot and sometimes it's difficult to keep track of what's happening. My absolute favorite part of the book came towards the end, at the trial of Lisbeth (this is on the back cover of the book, so I'm not giving anything away). The way Larsson wrote this part really kept my attention, and I found myself smiling at points. At this point, you know who you're rooting for, and when something happens in their favor, you just can't help but smile. At least, I couldn't. Everything in the book is building up to this point; everyone is scrambling to come up with an argument and defense for this trial. To see how it all came together was awesome. And definitely worth the wait.
Larsson also does a good job not leaving the reader with any questions. The book is quite long, but by the time you reach the end of the 600 pages, all of the loose ends have been tied up. And being that all the books are about this long, there were a lot of loose ends to tie up. The ending also doesn't really leave much for another book, which I think is a good thing, especially since Larsson is no longer alive to write anything else about Lisbeth Salander. And if anyone else tried, I think they would fail miserably. Overall, once you get passed the slow beginning of the series, you won't be disappointed. Because, from that point on, there is nothing slow about these books. There's never a dull moment in the life of Lisbeth Salander.