Adventure in Space (Legend of Otherland #3)

Description

The planet Acron is run by the mysterious four-eyed graymanoids, who covet the triptonite from which inventor Steven Charles' prototype spaceship is made. He is captured and forced to work to provide them with the formula. His young son Bunker and his friend, accidental stowaways on the ship's inaugural flight, escape. Can they overcome the mind control which keeps the planet's kidnapped population enslaved, and free Steven and their new friends?