Zahn, Timothy. Star wars #3

Originally published: New York : Bantam Spectra, 1993

Three book cycle includes: Volume 1 : Heir to the Empire --Volume 2 : Dark force rising -- Volume 3 : The last command

The embattled Republic reels from the attacks of Grant 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