Their adventures lead Tash, Zak, Hoole and DV-9 to Keva to seek out the remains of the evil scientist Borborygmus Gog's experiments. However, the Rebel Alliance and the Empire wish to gain control of Gog's secret weapon too.
Well, this book features our old friends Han, Luke, Leia, Chewie and the Droids and has them facing off against Darth Vader and his Stormtroopers. I also loved the bit in which Vader turns the power of the dark side against Eppon, the first of Gog's superwarriors. Which brings me onto this book's other good point, which is the way that it reveals that the experiments of the previous books were merely test cases for elements of Gog's masterpiece. We also discover the secret history between Hoole and Gog.
The story in general is pretty unimaginative and boring. Aside from the few scenes mentioned above, it's hardly worth reading.