For this weekend only, The Invisible City, first book in The Stolen Future trilogy, is free on Kindle.
The Invisible City is the story of Charles Clee, a World War I infantry officer scouting out an enemy position, who falls victim to an ambush and runs through a strange door to escape–all the way into the 863rd century. He is immediately pursued by the Time Police, charged with eliminating threats to the time stream by any means necessary.
Eluding the Time Police, Clee finds himself in a world of telepathy, of humans conquered by their own children returned from the stars, and of hideous creatures born of centuries of genetic engineering and recombination. And he finds himself wanted not only by the Time Police but by the Nuum, Earth’s alien overlords, who see in him the secret of time travel.
But Clee’s only goal is to go home–until he finds himself thrust into the violence of this future world, when a woman he meets is kidnapped before his eyes by a Nuum. Stung into action, he will embark on a voyage across the world, revealing wonders he could never imagine, and terrors he may never forget.
Graffiti on the Walls of Time 