Original illustration for "The Problem of Thor Bridge" by Alfred Gilbert, Strand Magazine (1922).

"The Problem of Thor Bridge" is a Sherlock Holmes short story by the British author Sir Arthur Conan Doyle. It was first published in two parts in the February and March 1922 issues of the Strand Magazine in England and the Hearst's International magazine in the United States. The story was later collected in The Casebook of Sherlock Holmes (1927). "The Problem of Thor Bridge" is the forty-sixth short story and the fiftieth tale of the Sherlock Holmes Canon.

In the story, the brilliant detective Sherlock Holmes is consulted by a wealthy American named Neil Gibson. Gibson's wife was killed recently. Her body was found at Thor Bridge, a stone bridge in Gibson's large estate, with a gunshot wound to the head. The governess to Gibson's children, Grace Dunbar, has been arrested. The case against the governess is strong: there was a note from her on the victim arranging the meeting at the bridge, and a revolver was found in her wardrobe. Gibson, however, is convinced of Miss Dunbar's innocence and asks Holmes to prove it. In the end, it is a small chip on the stone parapet that leads Holmes to the truth and saves Miss Dunbar's life.

"The Problem of Thor Bridge" is generally regarded as one of the finest among the later canonical tales. It is also notable for its opening paragraph which mentions Watson’s tin dispatchbox said to be filled with Holmes’ case records. Among the untold tales supposedly contained within is a case involving a "Mr. James Phillimore, who, stepping back into his own house to get his umbrella, was never more seen in this world." The intriguing disappearance case has inspired many pastiches as well as science fiction and magic branches of Sherlockian societies.

"The Problem of Thor Bridge" has been adapted for radio, television, and film.


On an October morning, Dr. Watson finds Sherlock Holmes in a particularly joyous mood at breakfast. It can only mean that Holmes has a new case. After the table is cleared, Holmes takes out a letter from Neil Gibson, a well-known American gold-mining magnate whose wife was killed recently at their estate in Hampshire. The evidence appeared clear at the coroner's inquest, and the case has now gone to the Assizes at Winchester. However, Gibson is convinced the accused, Miss Dunbar, is innocent. He proposes to come at eleven for consultation. Holmes has already reviewed the facts as reported in the papers, and he now summarizes them for Watson.

Gibson is of a violent and formidable character. His middle-aged wife was the victim and the suspect a very attractive governess in charge of their two children. Mrs. Gibson died from a bullet wound to the head. Her body was found around 11:00pm at the mouth of Thor Bridge, a stone bridge located a half a mile from the house in their large estate. No weapon was found at the scene. A revolver of the same caliber and missing one bullet was found in the governess' room, on the floor of the wardrobe. A note signed by the governess making an appointment at the bridge was found on the victim. The governess is known to have received attention from Gibson. She could not prove an alibi and was seen near the bridge.

As Holmes finishes, an unexpected visitor arrives. The nervous, frightened-looking man introduces himself as Marlow Bates, the manager of Gibson's estate. Bates says he has come to warn Holmes about Gibson. He describes Gibson as a villain who mistreated his wife simply because her physical charm had faded. Bates says everyone loved Mrs. Gibson, a passionate Brazilian woman, and hated the way her husband treated her. He advises Holmes not to trust Gibson then runs off before his employer catches him there.

The Problem of Thor Bridge 02

Gibson raises his fist in anger. Alfred Gilbert, Strand Magazine, 1922.

Neil Gibson arrives exactly at the appointed hour. He is tall and gaunt, and he has a remorseless face. He surveys Holmes and Watson with his cold gray eyes. Then, with a masterful air, he offers Holmes money and fame as rewards if he can save Miss Dunbar. Holmes refuses both and bluntly asks Gibson about his relationship with Miss Dunbar. When Gibson answers he never saw her without the children, Holmes rises from his chair and bids him good morning. Gibson rises in anger and asks what Holmes means by it. Holmes accuses him of lying, and Gibson raises his fist. Holmes calmly reaches for his pipe and suggests Gibson goes for a stroll and a quiet thought. Gibson regains his composure with an effort and, uttering a warning against crossing him, walks out.

Afterwards, Holmes reveals to Watson that he was simply bluffing, pretending he knew the truth about Gibson's relationship with the governess. He suspects Gibson cares more for Miss Dunbar than his late wife, and is certain he will return. As expected, Gibson returns shortly and announces he has decided Holmes is justified in getting down to the facts. Holmes asks for the truth and Gibson begins to talk.

Gibson met Maria Pinto when he was gold-hunting in Brazil. He was young and she was a rare beauty. She was also quite different from American women in her deep rich nature and passion. He loved her and married her. After the romance passed, however, Gibson realized he and his wife had nothing in common. His love faded but hers never did, and her love could not be killed however hard he tried. Then Grace Dunbar came, and Gibson could not help but be attracted to her. When he made his feelings known, Miss Dunbar wanted to leave immediately. Gibson swore he would never bother her again and she agreed to stay. Gibson explains that Miss Dunbar stayed mainly because she wanted to use her influence over him for good. Gibson used to play a hard game, thinking nothing of crushing the weak in the name of business. Miss Dunbar has taught him it is wrong to ruin others to make more money than one needs.

Gibson can only think of one explanation for what happened. His wife was bitterly jealous of Miss Dunbar's influence on him. She might have threatened Miss Dunbar with the gun and it could have gone off in a scuffle. Unfortunately, Miss Dunbar denies it. Holmes tells Gibson he will speak with Miss Dunbar, although he cannot promise what he finds will be to Gibson's liking.

While waiting for the permits to see Grace Dunbar, Holmes and Watson head out to Thor Place, Gibson's estate in Hampshire. Sergeant Coventry of the local police accompanies them. The policeman admits he is out of his depth. He welcomes Holmes' help and asks in confidence if Gibson himself may be guilty. He says the pistol they found came from Gibson's collection of firearms. It was one of a matching pair, although they have not found the other.

At the mouth of Thor Bridge, Sergeant Coventry points to the ground where Mrs. Gibson's body was found. Mrs. Gibson was shot at close range in the head, just behind the right temple. Her body lay on the back, and there were no signs of struggle. The sergeant says the note from the governess was clutched tightly in Mrs. Gibson's left hand. Holmes remarks that it proves the note could not have been placed after death as a false clue. Miss Dunbar admits writing the note which simply read "I will be at Thor Bridge at nine o'clock – G. Dunbar." Holmes thinks it odd that Mrs. Gibson held the note in her hand since the short message contained no information she required during the interview.

The Problem of Thor Bridge 04

Holmes strikes the ledge with his cane. Alfred Gilbert, Strand Magazine, 1922.

Holmes sits on the stone ledge for a few minutes looking around. Then he suddenly runs to the opposite parapet to examine the stonework with his magnifying glass. Sergeant Coventry informs him that they also saw the small chip on the ledge but, being fifteen feet from the body, felt it was unrelated. Holmes strikes the ledge several times with his cane and fails to leave a mark. The chip must have been made by a sharp blow. He also notes that the chip is on the lower ledge of the parapet, indicating the blow came from below. Holmes finishes examining the scene and they proceed to the house.

Gibson is out, but Marlow Bates shows them the house and Gibson's large collection of firearms. Bates again speaks badly of his employer and mentions that Gibson sleeps with a loaded revolver beside his bed to guard against his enemies. However, it appears Gibson did not go outside at all since returning home at 5:00pm on the day of the tragedy.

Holmes comments that the case against Miss Dunbar is strong except that the pistol was found in her wardrobe. Watson is shocked, since it seems the most damning evidence. Holmes explains that if one assumes she coolly premeditated the crime, then one must also assume she was prepared to cover it up. To put the weapon in her own wardrobe is inconsistent and therefore a deception is indicated. Whoever placed it there must be the criminal.

The following morning, Holmes and Watson visit Miss Dunbar in her cell accompanied by her lawyer. Holmes stresses the gravity of the situation, and Miss Dunbar promises to conceal nothing. She says Mrs. Gibson hated her, and she now sees that it was wrong of her to cause such unhappiness by staying. Holmes asks her to tell them what happened.

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Miss Dunbar runs away as Mrs. Gibson shrieks curses at her. Alfred Gilbert, Strand Magazine, 1922.

In the morning, Miss Dunbar found a note from Mrs. Gibson on the schoolroom table requesting a secret meeting after dinner. She was asked to destroy the letter and leave an answering note on the sundial. Miss Dunbar imagined the secrecy was due to Mrs. Gibson's fear of her husband. After dinner, Miss Dunbar went to the bridge as promised and saw for the first time the severity of Mrs. Gibson's hatred towards her. Mrs. Gibson poured her heart out and shrieked curses at Miss Dunbar. Covering her ears, Miss Dunbar ran back to her room. She stayed there until the alarm was raised about Mrs. Gibson. The pistol was found the following morning by the police. Miss Dunbar had never seen it before, and she is certain it was not there the previous morning when she tidied up the wardrobe. Anyone could have entered her room at meal time or during the hours she was with the children.

Holmes asks Miss Dunbar if she can explain the chip on the parapet. She thinks it is a coincidence, but Holmes is still bothered by it. He falls into an intense concentration and everyone watches him in silence. Then Holmes suddenly springs to his feet. He cries out "Come, Watson, come!" and, promising Miss Dunbar of a hopeful development, hurriedly takes his leave.

Traveling back to Thor Place, Holmes paces restlessly in the train. He finally sits down as they near the station and looks at Watson mischievously. Holmes asks Watson for his revolver and, examining it carefully, says "I believe your revolver is going to have a very intimate connection with the mystery which we are investigating." He assures Watson he is not joking but will offer no explanations.

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Holmes kneels down to examine the stonework and finds what he expected. Alfred Gilbert, Strand Magazine, 1922.

Holmes and Watson hire a trap at the station and drive to Sergeant Coventry's house. Holmes asks the policeman for ten yards of string, and they get a ball of twine from the village shop. As they approach the bridge, Holmes ties one end of the string to the handle of the revolver. Sergeant Coventry helps him mark the exact spot where the body was found. Holmes then finds a heavy stone, ties the other end of the string around it, and hangs the stone over the parapet. He walks back to the spot marked by the sergeant and stands with the revolver in his hand, the string pulled taut by the weight of the stone. Then he raises the pistol to his head and lets go. The revolver flies out of his hand, strikes the parapet violently, and falls into the water. Holmes kneels down to examine the stonework and finds another chip, identical to the first one, made by the revolver. Holmes asks Sergeant Coventry to get a grappling hook to recover Watson's revolver. He then tells the policeman he will find beside Watson's revolver the pistol, string, and weight used by the vindictive Mrs. Gibson to implicate Miss Dunbar.

Mrs. Gibson blamed Miss Dunbar for her husband's harsh treatment of her. She decided to end her own life in such a way as to make Miss Dunbar appear responsible. She cleverly obtained a note from Miss Dunbar then took one of her husband's revolvers for herself and placed the other in Miss Dunbar's wardrobe. Finally, she prepared the ingenious method to dispose of the revolver.[1] Having poured her heart out, she waited until Miss Dunbar was out of hearing range before shooting herself.

Watson's narrative ends with Holmes speculating that the remarkable woman and the formidable man they helped may join forces in the future for the good, Neil Gibson having learned something through the tragic experience.


The Mystery of Thor Bridge (1923), eleventh of the fifteen short silent films of The Last Adventures of Sherlock Holmes series starring Eille Norwood, is an adaptation of "The Problem of Thor Bridge."

The story was adapted for the BBC television Sherlock Holmes series starring Peter Cushing. It was first broadcast as the ninth episode of the second season on November 4, 1968.

The second episode of The Case-Book of Sherlock Holmes Granada TV series starring Jeremy Brett is a largely faithful adaptation of "The Problem of Thor Bridge." The episode first aired on the ITV network in the United Kingdom on February 28, 1991. One notable difference in the Granada version is that Neil Gibson does not come back for consultation after being dismissed by Holmes. Holmes' interview with Miss Dunbar is delayed not by paperwork but by the power play between Holmes and Gibson. When Gibson fails to return, Watson suggests using his letter to obtain permission to see Miss Dunbar. Holmes and Watson manage to trick their way into her cell but, before they can interview her, Gibson arrives and orders them out. Holmes discreetly arranges a meeting with Gibson's secretary, and the secretary comes to the meeting with a message from Gibson finally granting Holmes an interview at his estate.

"The Problem of Thor Bridge" has been dramatized many times for various radio adaptations of the Sherlock Holmes series. The first version, an episode of the Adventures of Sherlock Holmes show starring Richard Gordon, was broadcast in America on March 16, 1931 by NBC. Other notable radio adaptations include two versions done for The New Adventures of Sherlock Holmes series starring Basil Rathbone (broadcast on November 3, 1940, and on October 1, 1945), and an episode of The BBC Presents: Sherlock Holmes series with Clive Merrison in the role of Holmes (first aired on BBC Radio 4 on February 22, 1995).


  1. The method employed by Mrs. Gibson in the story to disguise her suicide was taken from a real-life case cited in Handbuch für Untersuchungsrichter (Handbook for Coroners, 1893) by Dr. Hans Gross, an Austrian professor of criminology. In the original case, the investigating officer found the fresh chip in the (wooden) parapet and suspected it was made by the murderer as he threw the weapon into the water. He dragged the stream and found the pistol tied to a large stone. The reason for the deception was not revenge but money. The dead man had been financially ruined, and he had taken out a large insurance on himself for the benefit of his family. The claim would not have been paid out in case of suicide.

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