by John W. Campbell (Author)

Mirans are desperate to escape their volatile home-world and bring a gigantic fleet to conquer Earth. Gresth Gkae leads the attack force in which each of their hundreds of ships is larger than Terrestrial spaceports. Nothing stands in the way of the invincible Miran Armada, except Buck Kendall, who has discovered the Ultimate Weapon and is now Earth's last hope for survival.