The novel basically covers the story of Darth Bane, the legendary Sith Lord who lived a thousand years before the Empire. Darth Bane is legendary for instituting the Rule of Two, which the Sith order followed for nearly a millenia.
This novel presents part of the New Sith Wars from the Sith point of view (although there are occasional cutaways to the Jedi troops). It also details the Sith training of Darth Bane, giving some interesting insights into the Dark Side of the Force. The novel itself reads very quickly. The writing is solid, but not exceptional. The story is extremely interesting (especially for Star Wars fans), but I felt that it didn't go into enough detail. Frankly, the novel could have been twice as long and it would have still held my interest. In my opinion, the writer wasted a chance to describe the Sith Academy in great detail and give the reader a more profound insight into the Sith order. Still, the book was highly enjoyable."Two there should be; no more, no less. One to embody power, the other to crave it."
If you're a Star Wars fan with an interest in the Sith (or Jedi), I would recommend this book.