Splinter Of The Mind's Eye

Stranded on a jumgle planet, Luke Skywalker and Princess Leia are caught in a desperate race aginst time and imperial stormtroopers to claim a gem which holds mysterious powers over the force...
Luke Skywalker expected trouble when he volunteered to follow Princess Leia on her mission to Circarpous to enlist their Rebel underground in the battle against the Empire. But the farm boy from Tatooine hadn't counted on an unscheduled landing in the swamplands of Mimban - the planet where the Kaiburr crystal lay, a mysterious gem that would give the one who possessed it such powers over the Force that he would be all but invincible. In the wrong hands, the crystal could be deadly.
Luke has to find the jewel and find it fast. Accompanied by his faithful droids R2-D2 and C-3PO. Luke and the Princess set out for the Temple of Pomojema - and a confrontation deep beneath the surface of an alien world with the most fearsome villain in the galaxy...