The Dark Rival Star Wars: Jedi Apprentice Book 2

Qui-Gon Jinn must face his past: his former apprentice, Xanatos, who has turned to the dark side of the Force, returns to fight Qui-Gon and lead Offworld Corporation as the major mining faction on Bandomeer. The Jedi Master must request the help of the boy he refused to have as his Padawan, the young Obi-Wan Kenobi.
During their fight against Xanatos and Offworld, Obi-Wan and Qui-Gon become close allies. However, Obi-Wan is soon captured by Offworld miners and forced to work as a slave on a deep sea mining facility, where Obi-Wan meets a Phindian named Guerra. After some near misses, Qui-Gon and Obi-Wan reunite in a showdown against Xanatos.
Xanatos escapes after nearly trapping Obi-Wan and Qui-Gon in a mining shaft. However, the mission brings Qui-Gon and Obi-Wan even closer. Finally, Obi-Wan is accepted as Qui-Gon's padawan learner.