Star Wars: The Thrawn Trilogy, Book 3: The Last Command

The embattled Republic reels from the attacks of Grand Admiral Thrawn, who has marshaled the remnants of the Imperial forces and driven the Rebels back with an abominable technology recovered from the Emperor's secret fortress: clone soldiers. As Thrawn mounts his final siege, Han and Chewbacca struggle to form a coalition of smugglers for a last-ditch attack against the empire, while Leia holds the Alliance together and prepares for the birth of her Jedi twins.

Overwhelmed by the ships and clones at Thrawn's command, the Republic has one last hope: sending a small force, led by Luke Skywalker, into the very stronghold that houses Thrawn's terrible cloning machines. There a final danger awaits, as the Dark Jedi C'baoth directs the battle against the Rebels and builds his strength to finish what he had already started: the destruction of Luke Skywalker.