In 1952 would-be beekeeper Tommy Beresford and his wife Tuppence are returning from Paris by train when they encounter Jane Finn, a scared young woman, who flees the train after her boyfriend Dominic is shot dead. Tuppence is intrigued that the newspapers do not mention the incident. Following an address dropped by Jane Tuppence visits a sleazy underground bookies where she is offered courier work in Paris by a man named Whittington and threatened before escaping. The Beresfords are informed by Tommy's uncle, Major Carter, of the Secret Service, that Dominic was a spy pursuing a Russian assassin known as Brown and had passed on a tape identifying him to Jane before he died. Working for Carter the couple advertise for information on Jane and meet her uncle, wealthy Julius Hersheimmer who is also looking for her and are also sent a photo linking the gunman to retired opera singer Rita Vandermeyer. Tuppence goes undercover as Rita's secretary whilst Tommy, helped by old army comrade ... Written by don @ minifie-1

Tommy is saved for the moment when Whittington wrongly assumes that he is Brown's money man, Clement Drennan, and he also briefly locates the incarcerated Jane Finn. Meanwhile Tuppence confides in barrister James Peel, a visitor to Rita's flat, her suspicions regarding the singer's involvement with Brown and an overheard plot to kill a high-flying American. Both Beresfords' cover is blown though Tuppence manages to escape from Rita and her sinister caller, bookie Lucky, bringing Carter to the flat to find Rita has been murdered. Tommy, on the other hand, is far from safe as the real Drennan turns up. Written by don @ minifie-1

Tommy is released by Whittington who threatens the Beresfords' son George unless Tommy steals a file from Carter's department, which, helped by Tuppence, he accomplishes though he is able to give Carter some information about a possible escape route for Brown. They return home to find the house ransacked and, whilst they locate the tape that Jane was carrying, Tommy unfortunately destroys it. They are not fooled however when Julius claims to be Brown and, discovering Brown's true identity, are able to prevent him from killing his intended victim as well as rescuing Jane Finn. Written by don @ minifie-1

Nuclear physicist Gilbert Worthing is abducted from a Norfolk RAF base along with secrets vital to national security. Carter gets Tommy to link up with agent Harrison but he is murdered by a hit-woman who also pursues Tuppence. Harrison's dying words concern N and M, two Russian spies, and lead Tommy to the Sans Souci hotel on the Norfolk coast where Gilbert was staying, to unmask the traitors. He is followed by Tuppence and together they meet a group of likely suspects including the glamorous Mrs Sprot, cocky young Carl Denim and two military types, Commander Haydock and Major Khan, the latter challenging Tuppence. Written by don @ minifie-1

Khan reveals to Tuppence that he too is after the Russian spy but for personal reasons and joins the Beresfords and the other guests at the Veterans Ball, where he is murdered. Soon afterwards Carter tells Tommy that N is demanding the release of several Communist prisoners or else a bomb will be detonated to destroy London. Tuppence suspects Mrs Sprot, who tells her that she was once Khan's lover whilst Tommy, seeing young Denim arrive at a deserted beach by boat, discovers an underground smugglers' passage leading up to the hotel. He investigates with Tuppence but they get separated. Written by don @ minifie-1

Attacked in the underground tunnel by his prime suspect, Tommy escapes and is rescued by an apparently friendly face, who imprisons Tommy along with the missing scientist Gilbert Worthing. Tuppence follows her own line of inquiry, collecting two unexpected allies to help her release the captives. However they still have to identify and outwit N, who possesses the means to trigger off the bomb unless their demands are met, and this leads to a confrontation which is literally the end of the pier show. Written by don @ minifie-1