Hugo Galvéz is a "Tin Man" -- an erstwhile human consciousness encoded and embodied in a completely artificial brain and body. He had once been the smartest human in Known Space. Now he was the smartest android but usually located in Unknown Space. Along with Murphy, his gynoid companion (and an Artificial Intelligence of the highest order herself), he prefers to explore the vast universe which had been opened up to humanity way back in the 25th Century.

Upon a failure of this couple to return to their home base, they were duplicated out of back-up memory and installed into new, upgraded bodies by Eithne Lamdagan. A pixie-ish young woman, Eithne is the 7th-generation granddaughter of Hugo and Murphy's old friend, Alyss Roaz. With a brand-new starship, the trio travels to a distant galaxy to find out what happened to the android's predecessors. What they find is something more dangerous than they possibly could have anticipated ... and yet, oddly familiar.