Arsenic in the Post by Ruskin Bond is a murder mystery covered in the book Death Under the Deodars. This story dates back to 1920s – it is narrated by Miss Ripley-Bean. When this story actually took place that time she was a young girl of twenty. Well, now she is a seventy year old spinster living in one of the rooms of the hotel Royal in Mussoorie. The story is narrated in the company of Nandu, the hotel owner, Lobo, the pianist, the princess of Harshil, and Ruskin Bond.
Mrs. Doreen Smith is a voluptuous married woman in her thirties. She lives in Meerut with his husband, Mr. Clarence Smith, and an eleven year old school-going daughter. She is bored of her life – she leads a sedentary lifestyle and her husband is not much of fun to her in bed. She is looking for some extra in life.
Soon, she comes in contact with a tall and dark and handsome man, Monty Summers. They get along together quite soon and secretly make love whenever they get chance. Monty Summers is married and lives in Agra. So, he often comes to Meerut on official duty and in the afternoon he comes to Doreen’s home. At times, Doreen visits him at his hotel place. The more they meet, the more they feel like doing it.
They are so excited by their love-making episodes that they hatched a plan to meet permanently, without caring a bit about their families. Monty Summers posted arsenic in an envelope to Doreen, along with it instructions on how to use it for killing Mr. Smith tactfully. Love is blind, so does lust.
Doreen and Monty succeed in giving a slow death to Mr. Smith. Soon, out of nowhere, in Agra a few men enter Monty’s house and kills his wife. His wife identifies one killer and screams out his name so aloud that her daughter who is sleeping in the next room hears that clearly. At the time of crime, Monty is not at home. He is out of town. When he comes back he handles the case to the police. Upon asking their daughter about the crime, she reveals one of the killers that her mother was screaming aloud. That man was a painter at Monty’s house. Police picks him up, he confesses Monty’s name in the murder.
Monty is arrested. From the deep investigation, it also comes out that he and Doreen killed Mr. Smith. Monty is hanged in Allahabad and Doreen is sent to jail for life imprisonment. Doreen is pregnant with Monty’s child. The baby is born, but she dies. What happens to the daughters of Monty and Mr. Smith remains a mystery – where did they go and how.