Preston served as a space patrol, but he was transferred to a postal ship. Now he must deliver mail to Ganymede. The new work turned out to be no less dangerous, because among the asteroids pirates were waiting for him, and on Ganymede - ice worms....

The planet itself was quite rigid - barren, deserted, forbidden; enough to stop the most adventurous and devoted. But they had to face a crazy genius who had the motto: death to all the Terrans!...