The story is set in the distant future where Earth and Mars are on the verge of war. The last spaceship to leave Mars headed for Earth is stopped and searched by Martian soldiers, who are looking for three saboteurs who destroyed a Martian city. "Attention, Inner-Flight ship Attention You are ordered to land at the Control Station on Deimos for inspection. Attention You are to land at once " The metallic rasp of the speaker echoed through the corridors of the great ship. The passengers glanced at each other uneasily, murmuring and peering out the port windows at the small speck below, the dot of rock that was the Martian checkpoint, Deimos. Stark terror ruled the Inner-Flight ship on that last Mars-Terra run. For the black-clad Leiters were on the prowl ... and the grim red planet was not far behind.