The action takes place at an unspecified point in the past. There are references to the laws of England having been different at the time at which the story takes place. A reference to "the sickness" probably refers to an outbreak of bubonic plague.
The story begins with the sudden death of a wealthy landowner named Francis Bowles. Squire Bowles' estate is inherited by his widow. She and Joseph Calvert, her son from a previous marriage, are unable to find any cash that belonged to Squire Bowles and conclude that he must have hidden his money somewhere. While searching through his stepfather's papers for clues to where he might have buried his treasure, Joseph Calvert discovers that Francis Bowles believed that it was possible for the living to summon the spirits of the recently deceased and force them to answer questions. Although Squire Bowles warned in his writings that the experience would most likely be an unpleasant one, Joseph Calvert carries out "the experiment" himself.
At the end of December, the Reverend Dr. Hall, the parish priest of a village in Norfolk, is writing a copy of the record of christenings, weddings and funerals which have taken place in his parish that year. He is interrupted by his housekeeper who tells him that Squire Francis Bowles has died. The priest is surprised because, although he had been ill, Squire Bowles appeared to have recovered. The cause of the Squire's sudden death is unknown, although it does not appear to have been a result of "the sickness" which has not yet spread to the area. The Reverend Dr. Hall goes to Squire Bowles' former home immediately to talk to the man's widow and his stepson Joseph Calvert.
The Squire's funeral takes place at ten o'clock the following evening. Curiously, Squire Bowles had requested that he be buried in the churchyard, rather than in the family vault. He had also asked to be buried without a coffin. Madam Bowles, the Squire's widow, does not attend the funeral, although nobody appears to notice that.
Madam Bowles inherits all of her late husband's property. She finds, however, that there is no cash in her house. She and her son Joseph Calvert search repeatedly but are unable to locate any hidden money. There are also no rumors about the Squire having a secret cache of coins. Joseph Calvert searches through his late stepfather's books and papers for any clues as to where the money could be hidden. He finds out that Francis Bowles believed in the "Middle State of the Soul", the idea that the spirits of the recently deceased remain under the protection of two angels for a certain amount of time and can be called back to the land of the living during that time. Squire Bowles often wrote to a certain Mr. Fowler of Gloucester about the subject. In his last letter, which he never sent or finished, Squire Bowles gives details of what is known as "the experiment", which he learned about from a book which he owned.
"The experiment" runs thus: Go to the grave of a recently deceased person. Call the dead person's name three times. Tell the dead person to ask permission of the two angels to come to you that night and answer any question you pose. Take some earth from the dead person's grave and wrap it in a cloth. Place the cloth under your pillow before you go to bed. The dead person will visit you that night, either in your dreams or in reality if you are still awake. In his letter, Francis Bowles warns that, in addition to answering any question that the living person poses, such as where buried treasure is located, the dead person is likely to say other things that the living person does not want to hear. It is also suggested that, once the ghost has been summoned, it could be difficult to send it away again. Nevertheless, believing that it will be the easiest way to find out where Squire Bowles' money is hidden, Joseph Calvert carries out "the experiment" that night. The cloth which he uses to collect soil from Francis Bowles' grave was one that was intended to be placed on the Squires' face before his burial. Madam Bowles claims that she did not have time to place the cloth on her late husband's face before the funeral.
The following morning, Joseph Calvert tells his mother that the ghost of Francis Bowles came to him at night and showed him his decomposed face. The angry ghost said that he would like Madam Bowles to see his face too. The terrified Joseph Calvert says that he does not want to stay in the house any longer.
Joseph Calvert and Madam Bowles go to Yarmouth to take a night boat to the Netherlands. The boat's skipper tells them that there will be one more passenger on the boat. The other passenger has no luggage, is hooded, speaks strangely and seems to know Madam Bowles and her son.
Madam Bowles and Joseph Calvert return home. Madam Bowles tells the Reverend Dr. Hall that she murdered her husband by poisoning him. She and her son are executed for the crime.
- Text of M.R. James' "The Experiment" on A Thin Ghost.rg. The story is still under copyright in the United States.