Star Wars (Volume 2 of a Three-book Cycle): Dark Force Rising

Five years after the return of the Jedi, the Republic stands threatened from within and without. Grand Admiral Thrawn has taken command of the remnants of the imperial fleet and has launched a campaign to destroy the Republic, planning to impose his iron will on the galaxy. As Princess Leia, pregnant with Jedi twins, risks her life to ally a proud and lethal race with the Republic, Han and Lando Calrissian race against time to find proof of treason within the Council. Most dangerous of all is a new Dark Jedi, insane and scheming to summon young Skywalker and to corrupt him to the Dark Side.