A Plague of Demons — Keith Laumer

THE SECRET MASTERS OF THE WORLD...WEREN'T HUMAN

When John Bravais went on a secret mission to observe a war in North Africa, he found out more than it was safe to know. Lupine-like aliens were harvesting the brains of the fallen, for an unknown purpose. And they were invisible to ordinary men. Bravais had been surgically transformed so that he was as strong as a tank and nearly as invulnerable, but he was only one man against thousands of aliens, against A Plague of Demons.

An alien probe has picked a human at random to test to his limits and find how serious an opponent the human race might be. But the aliens have picked the wrong man to Test to Destruction.

A ship is lost in action with only one survivor. He alone knows the secret that can stop the alien attackers in their tracks, but, accused by his own side of treason, he faces an ignominious End as a Hero.

One man has kept a lonely vigil on an isolated planet for years, watching for the alien enemy, forgotten by the bureaucracy that sent him there--then the enemy arrived, and the alarm signal had to be sent, in spite of the alien ship looming over the colony like a Thunderhead.

A full-length novel, five short novels, and more in an action-packed volume of the very best by the master of interstellar adventure.