
The recap below contains plot spoilers about Episode 15, "The Girl Who Was Death." If you haven't seen "The Girl Who Was Death" yet, you can watch the full episode online.
No. 6 acts out a fairy tale and meets up with a girl who believes they are made for each other: He is a born survivor, and she is a born killer.
Something has to give when a girl is a born killer and a man is a born survivor, so No. 6 (Patrick McGoohan) has an opponent worthy of him when he pits himself against the lovely-but-lethal Sonia (Justine Lord).
He takes over from the victim of a highly unusual accident, resulting from investigating the activities of a crazy scientist who is planning to destroy London.
No. 6 is soon aware that the killer intends that he should suffer a similar fate -- aware, too, that it's a girl, though he doesn't know her as Sonia, but simply by the name with which she introduces herself: Death.
Sonia is certainly ingenious, and she is present every time the murder attempt is made. Even if he doesn't see her, No. 6 hears her voice.
He outwits her when she tries to kill him at a cricket match with the substitution of a ball containing high explosives. And then with a poisoned drink in a public house, followed by an attempt at suffocation in a Turkish bath.
Each time she leaves a clue, in the event of failure, which will lead him to their next rendezvous. He finds himself in a wrestling bout with a killer and facing death in a Tunnel of Love on a fairground carousel in a ghost village, where mayhem runs through the butcher's, the baker's, and the candlestick-maker's and through one hair-raising event to another.
For Sonia, each failure is not only a challenge to further effort; it brings with it the realization that if she does kill him, what will be left for her? Life would be a bore. Won't he join her and her father? After all, her father is the scientist he is seeking.
But what really lies behind it all?