Tommy Beresford meets Prudence Cowley, also known as Tuppence, after the First World War. Seeking work, they team up and call themselves 'The Young Adventurers'. Fairly soon adventurous work involving a smuggled international treaty comes their way, and they are plunged into a world of crime and intrigue while they search for a mysterious woman known only as 'Jane Finn' and an arch criminal who calls himself Mr. Brown.
Tommy and Tuppence are now married and have purchased a business known as 'Blunt's Brilliant Detectives'.
When American millionares Hamilton and Phyllis Betts have a priceless pink pearl necklace stolen while they are staying with members of the British aristocracy, Blunt's Brilliant Detectives are called in to solve the case.
When a number of people are poisoned under the same roof, seemingly at random, Tommy and Tuppence investigate, only to find that it is unexpectedly difficult to find out who the killer is.
Major Barnard is mysteriously murdered while playing golf and Doris Evans is chief suspect. Tommy and Tuppence decide to investigate.
Monica Deane, who is a clergyman's daughter just like Tuppence, experiences frightening supernatural events at her boarding house and finds that her customers are being frightened away.
In despair she consults Tommy and Tuppence who decide to investigate.
Lady Merivale is found stabbed to death at a costume ball, and Captain Bingo Hale is arrested and charged with murder.
Tommy and Tuppence who had been at the costume ball disguised as Holmes and Watson, believe that he is innocent and make a few enquiries of their own.
Tommy and Tuppence are called in over the mysterious affair of the American Ambassador's missing boots.
At first the case seems to be a very straightforward one, but things take a much more sinister turn when it is discovered that drug smuggling at a chic London beauty Salon is going on under the noses of the Metropolitan Police Force.
Tommy and Tuppence have been conducting an investigation in the manner of G.K. Chesterton's Father Brown, with Tommy suitably dressed as a priest when suddenly a famous actress is murdered in her own cottage nearby.
It seems as though the murderer has made himself invisible, but he (or she?) reckons without the robust deductive powers of Blunt's Brilliant Detectives.
When Una Drake bets Montgomery Jones that she can be in two places at the same time, he sets out to prove her wrong, enlisting the services of Blunt's Brilliant Detectives along the way.
When the girl of his dreams turns out to be involved in the theft of some famous paintings, Montgomery sticks by her.
Intrepid explorer and fitness fanatic Gabriel Stavansson returns from his latest expedition abroad and finds that his fiancee has inexplicably gone missing. He consults Tommy and Tuppence at Blunt's Brilliant Detectives and commissions them to find the lady without delay.
Tommy and Tuppence finally track her to a sinister Nursing Home run by a doctor with a very bad reputation. Tuppence infiltrates the establishment in the guise of a famous Russian ballet dancer in need of peace and quiet, but things turn out to be very lively indeed.
Detective Inspector Marriot calls on Blunt's Brilliant Detectives and asks Tommy and Tuppence to hunt down a forger.
Somebody is passing forged notes at the exclusive Python Club in Upper Brook Street, and Detective Inspector Marriot feels that Tommy and Tuppence would be able to go under cover there better than any police officer. It is a very upper class establishment, and needs special attention.
Tommy and Tuppence agree with alacrity; Tommy invents the phrase 'the crackler' to describe a forger as they are going through their Edgar Wallace phase at Blunt's Brilliant Detectives and he believes that this word has the right feel to it. Alfred the office boy also assists in enquiries, going undercover as a motor cyclist.