Notes
The Silent Invaders, a standalone novel by Robert Silverberg.

This volume is a "dos-à-dos" omnibus in the Ace Double series. It also includes Battle on Venus by William F. Temple.

Previously published in a shorter form in Infinity Science Fiction (October 1958).

Publisher's Blurb – Page One
WHEN STAR SPIES CLASH . . .

Abner Harris came to Earth on a mission of extreme urgency. A Subject of the Spirit had no right to question his orders. And his orders said that the universe was in danger of enslavement by the pebble-skinned Medlins. And that the fight against their evil scheming called for him to assume the disguise of a flesh-and-blood Earthman.

But once in that new synthetic body, he made a mindnumbing discovery: that the real villains of space were neither the Medlins nor the people of Earth, but his own kind!

Suddenly he was alone, alienated from his own race, hated by the Medlins, and an impostor on Earth – no matter what side he chose, he'd be a traitor – but choose he must or forever remain a man without a planet!