Jedi Shadow (Star Wars: Young Jedi Knights Trilogy 1):

Jedi Shadow (Star Wars: Young Jedi Knights Trilogy 1): by Rebecca Moesta. mass_market edition. ISBN: 9780425186831.

Includes the complete novels: Heirs of the Force, Shadow Academy, and The Lost Ones HEIRS OF THE FORCE In the jungle outside the academy, the twins make a startling discovery—the remains of a crashed TIE fighter. The original pilot, an Imperial trooper, has been living wild in the jungles since his crash. Waiting for a chance to return to duty… SHADOW ACADEMY Thanks to the Dark Jedi Brakiss—Luke Skywalker’s former student—the dark side of the Force has a new training ground…the Shadow Academy… THE LOST ONES Jacen and Jaina could lose an old and dear friend. Zekk is wild and free in the underground mazes of Coruscant—and a perfect candidate for the Shadow Academy…