The Avengers "are needed" after reports that a motorist has repeatedly run over and supposedly killed the same person. Their investigations lead them to the country and the top secret Neoteric Research Unit, which is run by the appropriately-named Dr. Frank N. Stone, who has made a startlingly life-like robot of himself, so much so that Steed finds it hard to tell the two Stones apart.
—don @ minifie-1