Partners in Crime is a short story collection by British writer Agatha Christie, first published by Dodd, Mead and Company in the US in 1929[1][2] and in the UK by William Collins, Sons on 16 September of the same year.

The two tackle a series of cases – mimicking in each the style of a famous fictional detective of the period, including Sherlock Holmes and Christie's own Hercule Poirot.

Carter's particular request is that they watch for letters on blue paper sent to Mr Blunt from a purported ham merchant anxious to trace his refugee wife.

Later on, Tuppence ferrets out of Lady Laura's French maid, Elise, that her employer is something of a kleptomaniac, and five times in the past items have gone missing when she has been staying at friends' houses.

Their next visitor is Detective Inspector Dymchurch from Scotland Yard, a colleague of Marriot, who understands the need to keep a watch on the blue letters and is following Bower.

Tommy tells them that Tuppence has it, and writes a letter summoning her to the office; but he signs this "Francis" and shows them the General's wedding present as proof that this is his real name and not "Theodore Blunt".

A reluctant Tommy tries to distract her attention by pointing out to her the interesting fact that dots in the masthead of the newspaper indicate the different days on which the paper was produced, while his wife spots an advert in the personal column which reads, "I should go three hearts.

Merivale is perplexed as to what the motive could have been and is incensed at the suggestion from Marriot that the two were lovers and that Vere was threatening Hale who was paying attention to a rich American woman.

Marriot returns to the Beresford's with photographs of the fragment and the section of the costume it came from; he has the last link to convict Hale but Tuppence senses that he is far from satisfied with this conclusion to the case.

The International Detective Agency receives a visit from Gabriel Stavansson, the famous explorer, who has returned early from a two-year expedition to the North Pole.

Tommy and Tuppence impress him with their initial display of observational and deductive powers (because they read of his return in the Daily Mirror earlier that day) and he entrusts his case to them.

Lady Susan seems genuinely upset when told this news, but a telegram arrived as she and Stavansson were talking, signed by Hermione and addressed from Maldon, saying she was going to Monte Carlo.

Feeling foolish, the young detectives leave quickly, with Tommy commenting that there is no need to place the case in their records, in the fashion of Sherlock Holmes, as "It has absolutely no distinctive features."

Tommy receives a phone call from Mr Carter warning him and Tuppence that the people connected with the Russian letters on blue paper have become aware that they have taken Blunt's place, and to expect developments any time soon.

Having withdrawn to lick their wounds with cocktails in a hotel, they meet an old acquaintance, Mervyn Estcourt, known as "Bulger", who is in the company of the famous actress Gilda Glen.

Miss Glen is startled by this advice and Bulger laughs at her belief that the road in question is haunted by the ghost of a policeman who was killed and yet still walks his spectral beat.

The two witnesses on the course see at a distance the deterioration in his game and "Sessle" then goes to his bungalow where he meets Doris Evans as arranged and goes through a series of actions which lead to the innocent woman being arrested.

The Beresfords receive a professional visit from a smartly dressed young woman, Lois Hargreaves of Thurnly Grange, her house in the country.

What perturbs Miss Hargreaves is that the paper in which the chocolates were wrapped was re-used from a previous parcel sent to the Grange, evidenced by a small doodle of three intertwined fish that she drew on it.

The next day, Tommy and Tuppence plan to travel down to the Grange; before leaving, they read the news that Lois is dead, killed by a poison which also affected Dennis and Miss Logan.

The alibi is that on the previous Tuesday Miss Drake dined at a Soho restaurant, saw a West End show, and then had supper with a Mr le Marchant at the Savoy Hotel.

Armed with a photograph of Miss Drake and the knowledge of the methods of Inspector French, Tommy and Tuppence interview Mr le Marchant who confirms that he was with the young lady for part of the evening in question.

Tommy and Tuppence travel to the "Red House" and begin their investigations, harbouring suspicions that the old lady had hidden money in the building that would account for the remainder of her fortune being missing.

Tommy decides that their next line of action is to advertise for Miss O'Hara to come forward, even though they risk putting her on her guard if she was involved in tampering with the kit bag.

Two days later, Albert shows into Tommy's office a Miss Cicely March who is answering the advertisement, but before she can relate what she knows they are interrupted by a big, dark, Spanish-looking man who holds them up at gunpoint.

Preparing to take a taxi, Tommy notices that the cab has just refused a fare further down the road and, suspicious that they are being watched, insists on walking to Bond Street.

Mr Carter congratulates the Beresfords on their successes at the agency, but he gives them a warning that Moscow has become suspicious of the failure to hear from their agents, and that they have despatched a man to investigate.

In talking to Albert, Tommy is struck by an idea and races back to the Blitz where he and one of Carter's men return to Mrs Van Snyder's room.

The blurb of the first UK edition (which is carried on both the back of the dustjacket and opposite the title page) reads: This delightfully witty book will come as a pleasant surprise to all admirers of these ingenious detective thrillers for which Agatha Christie is famous.

makes delicious reading.The blurb was incorrect in that "Sapper's" Bulldog Drummond stories were not parodied, although the character and the situations that he encountered were briefly mentioned in The Adventure of the Sinister Stranger.