Parker Pyne Investigates is a short story collection written by Agatha Christie and first published in the UK by William Collins and Sons in November 1934.

Advertising his services in the "Personal" column of The Times, he works alongside his secretary Miss Lemon, novelist Ariadne Oliver, handsome "lounge lizard" Claude Luttrell and disguise artist Madeleine de Sara.

Maria goes to the address given and Parker Pyne instantly guesses the cause of her unhappiness from his knowledge of life and his previous occupation in statistics.

The next day Wilbraham receives note from Pyne instructing him to go to an address in Friar's Lane, Hampstead and call at a house named "Eaglemont."

In Friar's Lane, Wilbraham hears cries for help and going into an empty house sees a young blond-haired, blue-eyed woman being attacked by two black men.

The previous week she received a visit from an Australian lawyer who told her she might come into a legacy from business transacted by her late father but that it was dependent upon her having some papers of his.

They go to her room in lodgings in Notting Hill and in a slit in the lining of her father's old chest find a document which the Major recognises as being written in Swahili.

Parker Pyne visits Mrs Oliver, the novelist and congratulates her on the story she thought up for him to use with the Major and Freda, although he thinks the cellar of water was something of a cliché.

Lady Naomi Dortheimer is very taken with Jules, the dancer (in reality, Claude) and they are on the dancefloor when the lights suddenly go out, as arranged by Madeleine out in the hall.

Although he admits that there is a possibility that Iris is so completely in love with Jordan that the plan will fail, Pyne thinks the scheme has a ninety-seven percent chance of success and he charges Wade two hundred guineas, payable in advance.

Pyne knows of someone who could take on the case... Consequently, Mr. Roberts, his wife and children fortuitously staying with her mother, finds himself travelling by first-class sleeper train from London to Geneva and a hotel where he will receive further instructions.

The next day at the station, he soon bumps into a glamorous foreign girl who uses the correct password phrases with him and tells him to meet her in her next-door compartment after they have passed the border.

After she has gone, Pyne tells Claude Luttrell that the services of Dr. Antrobus will be needed... A week later he calls Mrs Rymer back to his office and introduces her to Nurse de Sara who takes the lady up one floor to the waiting Dr. Constantine.

Mrs Rymer is furious with Pyne but, bearing in mind the newspaper story of her transfer to a nursing home for mental delusions, she is not sure just what she can do or say that will be believed.

He is soon to set off on the 400 mi (640 km)-long journey across the Syrian Desert from Damascus to Baghdad by a Pullman motor coach that will traverse the wastes in some thirty-six hours instead of the months that the trip used to take.

There are various other people sharing the journey including the young attractive Netta Pryce and her austere aunt; three Royal Air Force officers called O'Rourke, Loftus and Williamson; a Mr Hensley of the Baghdad public works department; an old Etonian called Captain Smethurst; General Poli, an Italian; and an Armenian mother and her son.

The main news item discussed is the search for a crooked financier called Samuel Long, who is on the run and is rumoured to be in South America.

The pilot tells Pyne of his first two passengers, a young titled lady called Esther Carr and her beautiful companion who Schlagal fell in love with.

The supposed titled lady in front of him did not react to stories of high society events, but her face showed how much she missed the everyday life of ordinary people.

His companions are Caleb Blundell, an American millionaire, his daughter Carol and secretary, Jim Hurst, Sir Donald Marvel, a British MP, Doctor Carver, an archaeologist and Colonel Dubosc, a Frenchman.

Camping in the night, Doctor Carver tells the others of the Nabataeans, the traders who built the city and who were no more than professional racketeers who controlled the trade routes of the area.

Sir George married Lady Grayle to try to find a way out of his financial difficulties but the price he has paid is in having a difficult, bad-tempered, hypochondriac for a wife.

Pamela is not sympathetic to her aunt's complaints, telling Sir George that his wife's claims of illness are fraudulent and feeling appreciative of the problems Miss MacNaughton faces in dealing with her.

That night, Pyne is summoned to Lady Grayle's room where the woman is very ill. She dies, showing the unmistakable symptoms of strychnine poisoning.

Remembering when he saw the victim earlier on burning a letter in the lounge cabin, Pyne hurries there and retrieves a scrap of paper which has "...chet of dreams.

Pyne then sees Basil and asks him to write out his confession; he made love to the older lady but planned to slowly poison her and make sure the blame would be laid at the husband's door.

In the afternoon, Mrs. Peters comes back to her hotel after enjoying a relaxing few hours reading a detective novel in a shady spot only to find that a ransom note has been delivered – her son has been kidnapped and the demand is for ten thousand pounds sterling.

Her new friend notices her distracted manner during the evening meal and sends her a note enclosing his advert from The Times and announcing himself as none other than Parker Pyne.

When she shows Pyne the note, he concocts a plan to have a friend of his in Athens to make a paste copy of the diamonds and send this to the kidnappers.

"[4] In The Observer's issue of 18 November 1934, "Torquemada" (Edward Powys Mathers) stated that Christie was, "the only consistently inspired practitioner of an art where ingenuity and industry have so often to substitute for genius."