The Tuesday Night Club is a short story written by Agatha Christie and published in 1927. It was the first story featuring Miss Marple and would be the first chapter in the short story collection The Thirteen Problems in 1932.
A group of friends are meeting at the house of Miss Marple in St. Mary Mead. As well as the old lady herself, there is her nephew - the writer Raymond West - the artist Joyce Lemprière, Sir Henry Clithering (a former Scotland Yard commissioner), a clergyman called Dr. Pender, and Mr Petherick, a solicitor. The conversation turns to unsolved mysteries; Raymond, Joyce, Pender, and Petherick all claim that their professions are ideal for solving crimes. Joyce suggests that they form a club; every Tuesday night, a member of the group must tell of a real mystery, and the others will attempt to solve it. Sir Henry agrees to participate, and Miss Marple brightly volunteers herself to round out the group.
Sir Henry tells the first story of three people who sat down to a supper after which all of them fell ill, supposedly of food poisoning and one died as a result. The three people were a Mr and Mrs Jones and the wife's companion, Miss Clark, and it was Mrs Jones who died. Mr Jones was a commercial traveller and a maid in one of his hotels saw blotting paper he had used to write a letter whose decipherable phrases referred to his dependency on his wife's money, her death and "hundreds and thousands". The maid read of the death in a paper and, knowing relatives in the same village as the Jones's, wrote to them. This started a chain of gossip which led to the exhumation of the body and the discovery that Mrs Jones was poisoned by arsenic. There was further gossip linking Mr Jones to the doctor's daughter but there was nothing substantive there. The Jones' maid, Gladys, tearfully confirmed that all three people had been served the same meal of tinned lobster, bread and cheese and trifle. She had also prepared a bowl of cornflower for Mrs Jones to calm her stomach but Miss Clark had drunk this, despite the diet she was on for her constant weight problem. Jones also had a plausible reason behind the letter which was blotted in the hotel room.
The people in the room speak of their various theories as to who the murderer is but neglect to ask Miss Marple until Sir Henry politely points out the omission. Miss Marple witters on about a similar case involving a local family (to which Raymond cannot see any relevance) until she suddenly asks Sir Henry if Gladys confessed and that she hopes Mr Jones will hang for what he made the poor girl do. The letter in the hotel room was to Gladys and the reference to "hundreds and thousands" was to the small sweets on the top of trifle. They contained the arsenic which Miss Clark had not eaten (due to her diet) and Mr Jones probably avoided eating the poisoned portion. Sir Henry confirms Miss Marple is correct. Mr Jones had got Gladys pregnant and used a promise of marriage after his wife's death to induce the girl to commit murder. Having lost her baby after birth, Gladys confessed in a dying condition.