When the Inter-Planetary Corporation's starship Arcturus took off on a routine flight to Mars, it turned into a disastrous voyage. Attacked by a mysterious spaceship, the Arcturus crash-lands on Jupiter's moon Ganymede. The survivors must learn to master Ganymede's primeval terrors, construct a new spacecraft, and deal with the warring intelligences of the Jovian system. Of course, true spacehounds can do anything, given sufficient time, resources, and freedom from attack. A rousing interplanetary adventure in the classic tradition!