Watson's looking out at the street, and he sees someone he thinks is nuts. The madman is tall, dressed richly, but he's running hard and his face is twisted with strong emotion.
Watson can't figure out what's wrong with him, or why he's looking at the house numbers.
Holmes is excited: the crazy guy's coming to 221B Baker Street to consult Holmes.
In comes the madman, tearing at his hair and swaying where he stands. Suddenly, he jumps over and bangs his head on the wall, at which point Holmes steps in, leads the fellow to a chair, and soothes him.
The madman collects himself and says that he is in very, very deep trouble. He's a senior partner of the second largest private bank in London, and his name is Alexander Holder.
Holder has been to the police about his trouble, and the police suggested that he visit Holmes instead.
His firm has been issuing a lot of collateral-backed loans, or in other words, loans that are secured by the ponying-up of a piece of valuable property. So if you need six thousand bucks from Holder's bank, you might have to leave your car with him until you pay it back.
Holder has been conducting this kind of business with the most aristocratic families in England, using their paintings, silver (that's what he means by "plate"), or rare book collections.
So one day, a man from a very highly placed family comes to see Holder.
This nobleman needs a loan of fifty thousand pounds (that's U.S. $6,548,000 in today's money) immediately. Get this: he adds that he would have no trouble getting the money from his rich friends, but he wants to make this a business deal.
The nobleman adds that he'll be getting paid for something the following Monday, so he'll be able to return it promptly. (So, this is like a really, really high class version of a payday loan or a pawnshop arrangement.)
Holder agrees to lend him the money through Holder's firm, as long as there's some kind of security left behind.
The security the nobleman leaves is the titular Beryl Coronet, "one of the most precious public possessions of the empire" (Coronet.27). A coronet is a kind of crown, and beryl is a type of gem. There are 39 beryls in this particular coronet, set in gold. The value, says the nobleman, is twice that of the loan.
Holder feels a little uncomfortable taking the coronet as a security, since it's so famous and valuable, but the nobleman insists.
The nobleman says he'll be back for the thing on Monday, and they'll all be screwed if it somehow gets lost: there'll be a scandal, and the beryls are irreplaceable.
So Holder agrees to pay over the money and locks the coronet in his private safe.
That night, he takes the coronet home in preparation for having a special case made so that Holder can carry the coronet with him at all times. When at home, he locks the coronet in a bureau in his dressing room.
His house has six servants: a groom and a page who don't sleep in the house, three maids who have been with him for years and have never been any trouble, and one new maid, Lucy Parr, who's also of excellent character.
Holder's wife died years before and he has one son, Arthur, who's wild and untrustworthy with money. Arthur's a gambling man, and has lots of debts. Even though he has tried to break away from his high-stepping friends in the past, Arthur keeps getting drawn back in through the influence of a friend of his, Sir George Burwell.
Holder finds Burwell charming and glamorous, but he also appears deeply deceitful.
Holder also has a niece, Mary, who he adopted five years before when Holder's brother died. Holder loves her like a daughter, and she's the joy of his household.
One snafu, though: Arthur keeps proposing to Mary and she keeps saying no, even though Holder thinks Mary would be the kind of influence that could keep Arthur on the straight and narrow. (But wait, aren't they first cousins? Anyway...)
Holder continues his story: after locking up the coronet, he tells Arthur and Mary about his commission. He's sure that Lucy, the new maid, was out of the room at the time, but he's not sure if the door has been closed.
Arthur says Holder had better be careful: that bureau's easy to break into. He did it all the time as a child! And then he asks Holder for a loan of 200 pounds (today, U.S. $26,000 – and while we've asked our parents for a lot of loans, that does seem like kind of a lot).
Holder says no, and gets really angry over the whole thing.
Holder then goes around the house to make sure everything's locked up. He bumps into Mary, who asks if Holder gave Lucy (the maid) permission to leave the house tonight. Mary saw Lucy coming in by the back door unexpectedly.
Holder says Mary's right, that's not safe, and he'll speak to Lucy about it in the morning.
Holder goes off to bed.
At about two in the morning, he hears something that wakes him. It sounds like a window being closed. He feels a rush of adrenaline when he realizes he hears footsteps in the next room.
Holder slips into the next room and finds Arthur holding the coronet, from which one of the corners, with three beryls in it, is missing.
He immediately loses it, screaming at Arthur that he's a thief and a scoundrel, and that Arthur has now ruined Holder. He demands that Arthur return the jewels that are missing immediately.
Arthur gets pretty fed up at this, and says that he's leaving Holder's house in the morning. He won't stand for insults like this.
Holder threatens to call the police, and Arthur says, fine, then! You won't get anything from me.
The police come, and Holder tries one more time to get Arthur to produce the beryls. If he just gives the gems back, all will be forgiven and forgotten.
Arthur asks for five minutes of freedom before the arrest, but Holder won't allow it (since Arthur is obviously a flight risk).
So Arthur remains silent, and Holder has his own son arrested.
Every part of the house has been searched, especially Arthur's own room, yet the beryls have not turned up.
Holder asks Holmes to spare no expense in searching: he has lost his honor, his gems, and his son all in one night and has no idea what to do next.
Holmes asks if Holder gets many guests. Holder replies, none except his business partner and a few of Arthur's friends sometimes, including (often) Sir George Burnwell.
Mary and Holder both prefer to stay in at home.
They also both share the conviction that Arthur is guilty, what with being found with the damaged coronet in his hands and all.
Holmes is less sure of Arthur's guilt: why did he stay silent instead of making something up to clear himself of the crime?
And really, how is it possible that Arthur could break into the bureau, break off a piece of the coronet, and then magically find time to hide the three missing gems before going back to his dad's dressing room to fondle the main portion of the coronet? Ridiculous, says Holmes.
Holder looks desperate: if his son is innocent, why doesn't he just say so?
Holmes asks Holder to accompany him to his house in Streatham for further investigation. Watson comes too.
Holmes gets busy right away going over the grounds of the house (which is called "Fairbank"), so Holder and Watson go to the dining room to wait until Holmes comes back.
A woman comes into the room. She's very pale and her eyes are red with crying. (Contrary to what Holder says earlier) Mary is sure that Arthur is innocent. She wants Holder to release Arthur from prison.
Holmes returns at this point, and Mary asks that Holmes prove her cousin's innocence. Holmes agrees that Arthur is innocent, but he has to ask Mary a few questions.
Mary heard nothing that night before the sound of her uncle's shouting.
She also agrees that she locked all of the doors and windows the night before, and that they were all still locked the morning after the theft.
Mary points out that Lucy Parr, the maid, has a sweetheart, and that she might have overheard Holder's words about the coronet. Holmes catches Mary's implication that perhaps Lucy and her lover planned the robbery.
Mary adds that she saw Lucy coming in through the back door, and that she also caught a glimpse of Lucy's lover, a vegetable deliverer named Francis Prosper.
Holmes asks Mary if Prosper is a man with a wooden leg? Mary is amazed, and confirms it.
They then go up to the dressing room to examine the bureau and the damaged coronet. Holmes demonstrates how hard it would be to break off a piece of the coronet. He also notes that, if he somehow succeeded in doing so, it would make a loud snapping noise – something neither Mary nor Holder heard that night.
Holmes confirms (mysteriously) that Arthur was not wearing shoes or socks the night of the theft, and then continues his investigations outside.
Holmes, having seen all he needs to see, goes back to Baker Street after asking Holder to come to his apartment the next morning between 9 and 10am.
Watson knows that Holmes has solved the case, but he can't for the life of him figure out what that solution is.
As soon as they get home, Holmes dons a disguise as a "loafer," presumably someone without a job, and sets out again.
After a few hours, Holmes comes back for some tea and then goes out yet again, looking highly enthusiastic and happy about something.
Holmes isn't back by midnight, so Watson goes to bed without seeing him.
The next morning, Holmes is up bright and early, and he and Watson greet Holder just after nine. Holder looks terrible: this whole case has obviously been a terrible strain.
And now the final blow: his niece, Mary, has run away. Holder has found a note saying that Mary can't live with her uncle any longer, since she feels so bad about not preventing Arthur's slide into bad behavior. She asks Holder to not search for her or worry about her, because her future "is provided for" (Coronet.183).
Holmes seems to find this note very encouraging, for some reason. He asks Holder for a 4,000-pound check (today's U.S. $525,000) to recover the jewels.
Holder dutifully writes the check. So Holmes walks over to his desk, brings out a small triangle of gold with three jewels in it, and hands it over to Holder.
Holder is ecstatic.
Holmes is stern. He tells Holder that he owes Arthur an apology. Arthur has behaved throughout as a good son, which Holmes begins to explain to Holder.
First, and most painful: Mary has run away with Sir George Burnwell. It turns out that Burnwell is actually one of the worst scoundrels in England, and has managed to deceive Mary.
Mary is the one who sold out Holder: even though she loves her uncle, she loves Burnwell more.
Mary told Burnwell about the gold, left one of the windows unlocked, and took care to tell Holder about Lucy's side-door romance with Francis Prosper (to throw suspicion on poor Lucy).
Meanwhile, Arthur has gone to bed, but he sleeps badly because he's so worried about his gambling debts. He hears soft footsteps, goes to see who it was, spies Mary holding the coronet in her hand, and watches as she hands it off to someone through the open window.
At that moment, Arthur is horribly torn: he can't expose the woman he loves as a thief, but he also doesn't want to ruin Holder, his father. So as soon as Mary sneaks back up to her room, Arthur opens the unlocked window, jumps through it, and pursues the thief Burnwell.
Arthur catches him, grabs one half of the coronet while Burnwell clings to the other, something snaps, and Arthur finds that he had the coronet in his hands.
Arthur runs back to the house, coronet in hand, and sees that it has gotten twisted in the struggle. He tries to straighten the crown just as Holder walks in and accuses him of theft.
Because Arthur is such a noble guy in relation to women, he decides to keep Mary's secret rather than clearing his own name.
That's why Arthur wanted five minutes before his arrest: so that he could look for the missing piece of the coronet at the scene of the struggle. That's also why Mary screamed when she saw the remainder of the coronet in Arthur's hands – because she realized that Arthur knew that Burnwell tried to make off with the thing.
Holmes was able to work all of this out through careful observation of the dirt outside the house, which showed a bare-footed man in some kind of struggle with a man with boots. He also saw evidence that the booted man had waited for someone inside the house to pass him the gems – in other words, Mary.
Holmes works out that it has to be Sir George Burnwell because he's the only regular visitor they have to the house, and because Burnwell would trust in Arthur's silence –him opening up would bring shame on his own family.
So Holmes dresses up as an ordinary guy and strikes up a conversation with Burnwell's valet. He manages to buy an old pair of Burnwell's shoes from this servant, which he uses to compare with the boot prints in the alley next to Holder's house. They're a match!
Holmes then goes to see Burnwell, lays it all before him, and after a little scuffle, says that Holder's willing to pay a grand a jewel for the beryls (about U.S. $393,700 now). Burnwell's really bummed: he's already sold them for six hundred pounds (about U.S. $78,740 today) for all three.
Holmes goes to the fellow who bought the jewels and manages to buy them back for 3,000 pounds.
Holder is immensely grateful, and plans to immediately go apologize to his son. But he's still pretty broken up about Mary, and wonders whether Holmes could possibly trace her.
Holmes says that Mary is wherever Burnwell is, and that, whatever wrong she's done to Holder, she's going to suffer plenty of punishment at the hands of a jerk like Burnwell.