Labyrinth of Evil - James Luceno While this book is most certainly not an easy read (typical James Luceno), it is none-the-less fun and informative. Many of the Clone Wars novels (most notably The Cestus Deception and Jedi Trial) have been lacking or not very cohesive. Attack of the Clones movie only shows the beginning of the Clone Wars. And Revenge of the Sith ends the Clone Wars, leaving us, the audience, yearning for answers as to how we get from AotC to RotS.
This is where Labyrinth of Evil comes in.

Plot:
Anakin and Obi-Wan are fighting in the Outer Rim worlds, thrown their by our favorite almost-Emperor, Palpatine. They discover the mechno-chair used by Nute Gunray and discover the location of the feared General Grievous, finally revealed in fine detail.
Meanwhile, Bail Organa watches the changes in government and begins to worry about the outcome. He and a few others (Mon Mothma from Return of the Jedi) start the outlines of what will become the Rebel Alliance.
Anakin and Obi-Wan race closer and closer to the true identity of Darth Sidious as the events tumble into what was made into the movie, Revenge of the Sith.

Good:
Little references from all the Clone Wars novels (well, mostly the good ones, Yoda, Shatterpoint, etc.) are integrated into one cohesive work. The end blends perfectly with the beginning of RotS. I just loved reading each little detail that blended with AotC, the previous Clone Wars novels, and even The Phantom Menace, making sense of all the wanderings that previous novelists have done.

Bad:
Probably the only reason this does not receive a full five stars is the apparent conflictions with the Clone Wars Animated Shorts (almost as good as the movies). In the shorts, the end is completely different than that in Labyrinth of Evil. Anakin and Obi-Wan are on completely different systems with completely different reasons for being there. I still wonder how this is reconciled in Star Wars canon.

Dialogue/Sexual Situations/Violence:
No coarse language. No sexual situations. This is Star Wars during the Clone Wars--expect Star Wars type of violence (lightsabers, blasters, war, etc.).

Overall:
If you wonder about what happens to Anakin and Obi-Wan just before RotS, this will answer your questions. It is way, way better than The Approaching Storm (which merely told an unimportant, filler story) in this regard. Definitely worthwhile and important to truly understanding the nuances of Revenge of the Sith.