The unifying premise for this short story collection is the Tuesday Club: six people who meet socially one evening at Jane Marple's home and then decide to meet regularly each Tuesday night to solve a mystery which a group member must relate.
"The Tuesday Night Club" (December, 1927) Raymond West, the writer, is visiting his aunt Jane Marple at her home in St. Mary Mead, and is playing host to a few friends when he opens the subject of unsolved mysteries. The company, representing several professions and outlooks on life, offers different opinions on who is best equipped to solve such problems, and they decide to put the issue to a practical test. Every Tuesday, one member will tell the story of a problem to which he or she knows the answer, and the others will try to solve it.
Unsurprisingly, Sir Henry Clithering, lately retired from Scotland Yard, is asked to tell his story first, and he selects a case that wasn't solved when it first arose; the solution has just come into his hands, and an arrest will soon be made. Middle-aged Mr. and Mrs. Jones, together with her companion Miss Clark, all shared a meal featuring tinned lobster just after Mr. Jones' return from a business trip; they were ill afterwards, and Mrs. Jones (who had the money) died of it. Local gossip prompted an official autopsy that found Mrs. Jones had died of arsenical poison, but no one seemed to have had an opportunity to poison her without poisoning everyone at the meal.
"The Idol House of Astarte", a.k.a. "The 'Supernatural' Murder" (1928) Dr. Pender, an elderly clergyman, tells a story of a tragic death at a house party in his youth. Richard Hayden liked the fancy that Silent Grove near his home was once a sacred grove, and had a kind of folly built to encourage the fancy. Diana Maberly, one of the beauties of the season who was flirting with Richard, his cousin Elliot, and a few others as well, took the fancy to heart, and asked for a costume party. But things went tragically awry.
"Ingots of Gold", a.k.a. "Miss Marple and the Golden Galleon" (1928) Raymond West doesn't know the answer to his problem, but Sir Henry does, and Miss Marple deduces it. He made the acquaintance of an authority on Elizabethan times, who was preparing a treasure-hunting expedition to salvage gold from the wreck of an Armada galleon off Cornwall. But the police were interested in quite another problem: how someone managed to make a lot of gold bullion vanish from the strongroom of the _Otranto_ - if it was ever aboard at all.
"The Bloodstained Pavement" (1928) Joyce Lampiere, like many another painter, stayed in a Cornish village to paint self-consciously picturesque scenery: in this case, the Polharwith Arms (give or take waiting for a boring couple and their flamboyantly dressed companion to get out of the way). A fisherman watching her sketch tells her the story of the near-destruction of the village by the Spanish, and she's annoyed that some of it got into her sketch - bloodstains on the pavement outside the hotel. But she looks up to find that she only painted what she'd really seen, although the fisherman didn't see it...
"Motive versus Opportunity" (1928) Locked-room. Mr. Petherick, Miss Marple's lawyer. After the death of his little granddaughter, Simon Clode made his grown nephew and nieces his heirs. Unfortunately, he got interested in spiritualism, and proposed to make a will leaving his estate to his favorite medium, Mrs. Spragg, against Mr. Petherick's advice (who marked her down as an old fraud). But when the time came to probate the will, Mr. Petherick's safe contained only blank sheets of paper, and nobody seemed to have both motive and opportunity to pull the switch.
"The Thumb Mark of St. Peter", a.k.a. "Ask and You Shall Receive" (1928) Miss Marple herself presents a problem that none of the others can work out. Her niece Mabel made an unfortuate marriage to a man with insanity in his family. After one particularly ugly quarrel, her husband became ill in the night and died suddenly. Not overly grief-stricken, Mabel didn't send for her aunt until she realized that she was suspected of poisoning her husband...