Brother Assassin — Fred Saberhagen

HUMANITY VS. THE DEATH MACHINES ON THE STRANGEST PLANET IN THE GALAXY...

On the planet Sirgol the death machines have a unique and subtle mode of attack -- for in all the galaxy only on Sirgol is time travel possible. Now, fought to a standstill in the present, they have turned to the past in an attempt to destroy the very roots of life. The time and place of the next attack has been pinpointed: the Berserkers will try to eliminate Vincent Vincento, an early genius whose loss will cost mankind a hundred years of progress in the physical sciences.

Derron Odegard, one of the elite corps of Time Operatives, has the toughest assignment in Sirgol's history: protect Vincento at any cost. Derron's expertise is second to none, but even he has a lot to learn -- about the kinds of power that can shift the axis of a world, and about the power of the human soul itself ...