What is the summary of "The Adventure of the Blue Carbuncle"?

Around Christmastime in London, Watson drops in on Holmes to find him contemplating a battered hat that was dropped in a street fight and brought to him, along with an abandoned Christmas goose with a tag with the name "Henry Baker" on it, by Mr. Peterson, a commissionaire. Since Henry Baker is a very common name in London, there is little hope of finding the owner of the hat and goose, so Sherlock sends Peterson home with the goose and keeps the hat.

Peterson returns, having discovered the Blue Carbuncle, a famous jewel that has recently gone missing, in the goose's crop while cooking it. The Blue Carbuncle went missing from the Countess of Morcar's hotel suite, and the police have arrested John Horner, the hotel plumber. However, with the appearance of the Blue Carbuncle in Peterson's goose, Holmes believes the police may have the wrong man.

Holmes places an advertisement about the lost goose and hat, and Henry Baker appears to claim his goose. When Holmes tests him and offers him a replacement goose rather than the cooked insides of his original goose, Henry Baker accepts, showing that he did not know the jewel was inside his original goose. He tells Holmes that he got the goose from Alpha Inn, a local pub.

Holmes and Watson go to the Alpha Inn and learn from the landlord that the geese he sells are acquired from a merchant in Covent Garden. When Holmes and Watson go there to question the merchant, Breckenridge, he gets upset, saying that he keeps being bothered about where his geese come from, revealing that someone else has been hunting down the goose. Breckenridge also reveals that the geese are bred by a Mrs. Oakshot.

As Holmes and Watson start to leave to find Mrs. Oakshot, a small man, James Ryder, appears and harasses Breckenridge about the geese. Believing him to be the guilty party in the jewel's disappearance, Holmes lures Ryder back to 221B Baker Street, telling him that they found his goose.

Once there, Holmes tells Ryder that he knows about the jewel, and Ryder, worried that he will be turned over to the police, places the blame on Catherine Cusack, the countess's maid, for the disappearance of the jewel, but admits that he was her accomplice. He says he was terrified of being arrested so he decided to hide the jewel inside one of the geese his sister, Mrs. Oakshot, was breeding. He tried to pick one with distinctive markings but did not realize that two of the geese had the same bar across their tails. He took the wrong goose home, and once he realized his mistake, it was too late.

Ryder begs Holmes for mercy, and Holmes relents, believing that he has already learned his lesson and that sending Ryder to prison will just make him a hardened criminal. He lets Ryder go, on the condition that he flee the continent and not testify against Horner.

Describe the story of "The Adventure of the Blue Carbuncle."

In this 1892 short story by Sir Arthur Conan Doyle, a combination of coincidences and mix-ups allow Sherlock Holmes to solve the mystery of a stolen carbuncle, a precious gem.

The Christmas season, however—not a jewel—opens the story in what Holmes describes to Watson as one of those "whimsical little incidents." Peterson, a "very honest" police officer, approaches Holmes with a hat and a Christmas goose he has retrieved after the man who was carrying the goose was attacked. Both the assailant and the owner fled from the policeman, so Peterson comes to Holmes wondering if the owner of the items can be tracked down. As Holmes thinks this is impossible, Peterson takes the goose home to cook, and Holmes keeps the hat.

Unrelated to Holmes, a priceless blue carbuncle is stolen from the Countess of Morcar's hotel room. Unlike the usual carbuncle, a bright red gem, this stone, which was found in China, is blue.

However, the two incidents come together when the blue carbuncle is found inside the goose. Now, it becomes imperative to track the owner of the goose, and Holmes is on the trail.

More than just a mystery, ethics and justice come into play. John Horner, an innocent man who happens to have a criminal record, is framed for the crime. The real thieves are the countess's maid and James Ryder, the mastermind behind the plot and a fearful, cringing little man. Holmes, who has the freedom to make moral determinations that a police officer might not, decides to let Ryder flee to the European continent, determining that serving jail time would only harden him into a real criminal. Plus, once he is gone, Horner will go free because there is now no case against him.

Thematically, therefore, the story questions the value of imprisonment as a form of justice, and Holmes enacts some of the mercy we associate with the Christmas season. As Holmes says to Watson:

This fellow will not go wrong again; he is too terribly frightened. Send him to gaol now, and you make him a gaol-bird for life. Besides, it is the season of forgiveness. Chance has put in our way a most singular and whimsical problem, and its solution is its own reward.