"The Adventure of the Red Circle" is a Sherlock Holmes short story by the British author Sir Arthur Conan Doyle. It first appeared in print in two parts in the March and April 1911 issues of The Strand magazine. It would be published again in October 1917 as part of the anthology His Last Bow.
The plot is set in motion when a woman named Mrs. Warren seeks the help of the brilliant consulting detective Sherlock Holmes. Ten days earlier, Mrs. Warren rented a room to a young man. She has not seen her lodger since that day, although she hears him walking around in his room constantly. She is worried that there is some reason why the man has gone into hiding. Although the case at first appears to be trivial, Holmes soon discovers that it is connected to serious crime.
The story has been adapted for radio and television.
A landlady named Mrs. Warren comes to the apartment which is shared by the detective Sherlock Holmes and his friend Dr. Watson. Holmes is initially reluctant to accept Mrs. Warren's case, which does not sound at all serious to him. Mrs. Warren says that a previous lodger of hers once made use of Holmes' services and that he often spoke afterwards about how intelligent and kind Holmes was. Flattered, Holmes agrees to listen to the woman.
Ten days earlier, a man rented a room in the upper story of Mrs. Warren's house. The man was aged about thirty and had a beard and mustache. He spoke good English but his accent suggested that he was foreign. He offered Mrs. Warren twice the weekly rent that she asked for and offered to give her two weeks rent in advance in cash if she agreed to certain conditions. The man asked to be given a key to the house and never to be disturbed under any circumstances. He also asked that all meals be brought up on a tray and left on a chair outside his room when he rang for them. After he had finished a meal, he would ring again and the tray would be taken away from the chair outside the room.
Mrs. Warren says that the lodger only went out once, on the evening that he arrived. It was after midnight when he returned and Mrs. Warren, her husband and their young female servant had gone to bed. Since then, nobody has seen the lodger, although Mrs. Warren hears him walking around quickly in his room all day. The lodger has not left his room and nobody else has entered it. The lodger has occasionally requested other items, by notes written entirely in capital letters on small pieces of paper. Mrs. Warren shows Holmes notes which read "SOAP", "MATCH", "DAILY GAZETTE". Mrs. Warren adds that she has left the lodger a copy of the Daily Gazette newspaper every morning with his breakfast.
Having heard that Holmes can determine a lot from apparently insignificant things, Mrs. Warren shows him some matches and a cigarette end which her lodger left on his breakfast tray that morning. Holmes immediately notices that the person who smoked the cigarette did not have a beard or a mustache.
After Mrs. Warren has gone, Holmes says that he believes that the person who is now occupying the room is not the person who rented it from Mrs. Warren. The evidence being the lodger returning late at night in order to be unseen, the cigarette smoked by someone without facial hair and the fact that one note read "MATCH" instead of "MATCHES". Holmes believes that the current occupant of the room does not speak English as well as the man who spoke to Mrs. Warren and probably got the word "match" out of a dictionary.
Holmes looks in the personals section of recent editions of the Daily Gazette. He sees several messages, beginning two days after Mrs. Warren rented her room, which are signed G. The following morning, Holmes looks at that day's edition of the Daily Gazette and sees the message, "High red house with white stone facings. Third floor, second window left. After dusk. G,"
Mrs. Warren returns. She says that her husband was abducted on his way to work that morning. Two or three men threw a coat over his head and bundled him into a cab. Mr. Warren did not see the men's faces or hear them speak. After an hour, Mr. Warren was thrown out of the cab and he had to take a bus home. Holmes says that Mr. Warren's abductors mistook him for the lodger and let him go after they realized their mistake. Mrs. Warren wants to throw the lodger out of her house at once. Holmes, however, wants to see the lodger first.
Holmes and Watson are taken to Mrs. Warren's house. On the way, they see that a house across the road matches the description "red house with white stone facings" from the notice in that day's Daily Gazette. Holmes and Watson hide in a room across from that of the lodger. After Mrs. Warren brings the lodger's lunch, Holmes and Watson see the hands and face of a woman at the lodger's door. Holmes realizes that the occupant of the room wrote notes entirely in capitals in order to disguise her feminine handwriting. He deduces that the case involves a couple seeking refuge in London. The husband is evidently trying to keep his wife as safe as possible while he attends to some dangerous business. The couple's enemies are evidently not aware that the wife, and not the husband, is lodging in Mrs. Warren's house.
Following the instructions from the notice in the Daily Gazette, Holmes and Watson return to Mrs. Warren's house after dusk. They look at the second window from the left on the third floor of the house indicate in the notice. They see someone use a light to repeatedly flash out the word attenta and then repeatedly flash out the word pericolo. Holmes recognizes the Italian words for "beware" and "danger". While flashing out the word pericolo, the sender suddenly stops.
Holmes and Watson go over to the red house. They find Inspector Gregson of Scotland Yard standing outside the building. Inspector Gregson reveals that an American, Mr. Leverton from the Pinkerton detective agency is also watching the building. Gregson and Leverson are both looking for a man named Gorgiano, a member of the criminal organizaton known as the Red Circle who is responsible for at least fifty murders in the United States. Leverson says that he has seen three people leave the building but none of them were Gorgiano. Holmes tells Gregson and Leverson about the signals which suddenly stopped. Holmes, Watson, Gregson and Leverson go up to investigate. They find the dead body of a large clean shaven man. The man had been stabbed in the throat and a red circle of blood had been drawn around his head. Leverson recognizes the dead man as Gorgiano. Holmes asks Leverson if one of the people who left the building was a man of about thirty with a beard and mustache. Leverson says that is correct.
Sherlock Holmes uses the light to signal at the window. Thinking that the signal is from her husband, the woman that Holmes and Watson briefly saw earlier comes over from Mrs. Warren's house. She introduces herself as Emilia Lucca. She is delighted to see that Gorgiano is dead and realizes that her husband, Gennaro Lucca, killed him.
Although her English is not very good, Emilia Lucca is able to make Holmes, Watson, Leverson and Gregson understand her story. She was born in the town of Poslippo near Naples. Her father was an important man in the district. He did not approve of her love for the poor Gennaro Lucca. She and Gennaro ran away, got married and went to New York, Emilia having sold her jewels to pay for the journey. In New York, Gennaro was given a job by Mr. Castalotte who ran a fruit importing business. Mr. Castalotte loved Gennaro and Emilia as if they were his son and daughter.
One evening, Gennaro brought home a man named Gorgiano, also from Poslippo. Gorgiano often came to their house afterwards. Emilia never liked Gorgiano and soon realized Gennaro did not like him either and was afraid of him. Gennaro revealed that, many years earlier, he had joined the Neapolitan Red Circle. He had hoped that he had left the crime organization behind when he went to America. He then saw Gorgiano, the same man who had inducted him into the Red Circle in Naples. Gorgiano had come to New York to start an American branch of the organization. One evening, Gorgiano came to Gennaro and Emilia's house before Genarro returned home. He grabbed hold of Emilia and began kissing her. Genarro returned. He confronted Gorgiano but Gorgiano knocked him unconscious and fled.
The Red Circle financed itself by demanding protection money from wealthy Italians. Mr. Castalotte refused to pay. It was decided that an example be made of him. Lots were drawn to determine who would murder him. Emilia thinks that the process was rigged in some way because Genarro drew the lot to kill Mr. Castalotte. Instead of killing him, Gennaro sent a warning to Mr. Castalotte. Gennaro and Emilia fled to London but Gorgiano followed them.
It is uncertain whether or not Gennaro Lucca will be tried for Gorgiano's murder. Mr. Leverson thinks that the people of New York owe Gennaro a vote of thanks for ridding them of the criminal.
The episode "Mrs. Warren's Lodger" from the American radio series The New Adventures of Sherlock Holmes, starring Basil Rathbone as Holmes and Nigel Bruce as Watson, is an adaptation of "The Adventure of the Red Circle". The program first aired on the NBC Blue Network on December 7, 1941, the day of the Japanese attack on Pearl Harbor which brought the United States into World War II. The episode's East Coast broadcast was interrupted by an announcement that President Franklin D. Roosevelt would be addressing the nation (giving what would later come to be known as the Infamy Speech) at twelve o'clock the following afternoon.
A British radio adaptation, starring Clive Merrison as Holmes and Michael Williams as Watson, was first broadcast on BBC Radio 4 in the United Kingdom on January 19, 1994. Mrs. Warren is played by veteran British comedy actress Joan Sims.
The fourth episode of The Memoirs of Sherlock Holmes, the fourth and final Granada TV series starring Jeremy Brett as Holmes, is an adaptation of "The Adventure of the Red Circle". It first aired on the ITV network in the United Kingdom on March 28, 1994. Veteran British comedy actor Kenneth Connor appears in the episode as Mr. Warren.