第 1 季，第 5 集: Tommy and Tuppence think they are getting somewhere until their first major suspect Major Khan is killed at the local Veterans Ball. It turns out Khan was looking for N too, for a different reason, and N got to him first. And so Tommy and Tuppence turn their attention to their fellow occupants of the Sans Souci to find the potential nuclear bomb thief. Tommy has his eyes on Carl Denim, a shifty young beatnik who loves to flirt (especially with Tuppence) and is spending a lot of unexplained time around the coast, whereas Tuppence is convinced the culprit is Mrs Sprot, a glamorous and sensual woman, apparently married, but traveling alone. She was certainly in Khan’s room the night of his death, but was it to cover up their affair, or the fact that she is N? There are so many potential suspects and dead ends. Tommy and Tuppence can’t help but get their wires crossed and let their guard down. Tommy inadvertently ends up in the lion’s den. He finds himself in the home of an apparently kindly old sea dog, Commander Haydock, who is revealed to be not what he seems to be.