“Yes, the great yellow Mazarin stone. I’ve cast my net and I have my fish. But I have not got the stone. What is the use of taking them? We can make the world a better place by laying them by the heels. But that is not what I am out for. It’s the stone I want.”

“And is this Count Sylvius one of your fish?”

“Yes, and he’s a shark. He bites. The other is Sam Merton the boxer. Not a bad fellow, Sam, but the Count has used him. Sam’s not a shark. He is a great big silly bull-headed gudgeon. But he is flopping about in my net all the same.”

“Where is this Count Sylvius?”

“I’ve been at his very elbow all the morning. You‘ve seen me as an old lady, Watson. I was never more convincing. He actually picked up my parasol for me once. ‘By your leave, madame,’ said he — half-ltalian, you know, and with the Southern graces of manner when in the mood, but a devil incarnate in the other mood. Life is full of whimsical happenings, Watson.”

“It might have been tragedy.”

“Well, perhaps it might. I followed him to old Straubenzee’s workshop in the Minories. Straubenzee made made the air-gun — a very pretty bit of work, as I understand, and I rather fancy it is in the opposite window at the present moment. Have you seen the dummy? Of course, Billy showed it to you. Well, it may get a bullet through its beautiful head at any moment. Ah, Billy, what is it?”

The boy had reappeared in the room with a card upon a tray. Holmes glanced at it with raised eyebrows and an amused smile.

“The man himself. I had hardly expected this. Grasp the nettle, Watson! A man of nerve. Possibly you have heard of his reputation as a shooter of big game. It would indeed be a triumphant ending to his excellent sporting record if he added me to his bag. This is a proof that he feels my toe very close behind his heel.”

“Send for the police.”

“I probably shall. But not just yet. Would you glance carefully out of the window, Watson, and see if anyone is hanging about in the street?”

Watson looked warily round the edge of the curtain.

“Yes, there is one rough fellow near the door.”

“That will be Sam Merton — the faithful but rather fatuous Sam. Where is this gentleman, Billy?”

“In the waiting-room, sir.”

“Show him up when I ring.”

“Yes, sir.”

“If I am not in the room, show him in all the same.”

“Yes, sir.”

Watson waited until the door was closed, and then he turned earnestly to his companion.

“Look here, Holmes, this is simply impossible. This is a desperate man, who sticks at nothing. He may have come to murder you.”

“I should not be surprised.”

“I insist upon staying with you.”

“You would be horribly in the way.”

“In his way?”

“No, my dear fellow — in my way.”

"Whom did she ask for?"

"M. Michel Beaumont," replied the servant.

"Queer. And why has she called?"

"All she said was that it was about the Enghien business... So I thought that... "

"What! The Enghien business! Then she knows that I am mixed up in that business... She knows that, by applying here... "

"I could not get anything out of her, but I thought, all the same, that I had better let her in."

"Quite right. Where is she?"

"In the drawing-room. I've put on the lights."

Lupin walked briskly across the hall and opened the door of the drawing-room:

"What are you talking about?" he said, to his man. "There's no one here."

"No one here?" said Achille, running up.

And the room, in fact, was empty.

"Well, on my word, this takes the cake!" cried the servant. "It wasn't twenty minutes ago that I came and had a look, to make sure. She was sitting over there. And there's nothing wrong with my eyesight, you know."

"Look here, look here," said Lupin, irritably. "Where were you while the woman was waiting?"

"In the hail, governor! I never left the hail for a second! I should have seen her go out, blow it!"

"Still, she's not here now... "

"So I see," moaned the man, quite flabbergasted.

"She must have got tired of waiting and gone away. But, dash it all, I should like to know how she got out!"

"How she got out?" said Lupin. "It doesn't take a wizard to tell that."

"What do you mean?"

"She got out through the window. Look, it's still ajar We are on the ground-floor... The street is almost always deserted, in the evenings. There's no doubt about it."

He had looked around him and satisfied himself that nothing had been taken away or moved. The room, for that matter, contained no knicknack of any value, no important paper that might have explained the woman's visit, followed by her sudden disappearance. And yet why that inexplicable flight?

"Has any one telephoned?" he asked.

"No."

"Any letters?"

"Yes, one letter by the last post."

"Where is it?"

"I put it on your mantel-piece, governor, as usual."

Lupin's bedroom was next to the drawing-room, but Lupin had permanently bolted the door between the two. He, therefore, had to go through the hall again.

Lupin switched on the electric light and, the next moment, said:

"I don't see it... "

"Yes... I put it next to the flower-bowl."

"There's nothing here at all."

"You must be looking in the wrong place, governor."

But Achille moved the bowl, lifted the clock, bent down to the grate, in vain: the letter was not there.

"Oh blast it, blast it!" he muttered. "She's done it... she's taken it... And then, when she had the letter, she cleared out... Oh, the slut!... "

Lupin said:

"You're mad! There's no way through between the two rooms."

"Then who did take it, governor?"

They were both of them silent. Lupin strove to control his anger and collect his ideas. He asked:

"Did you look at the envelope?"

"Yes."

"Anything particular about it?"

""Yes, it looked as if it had been written in a hurry, or scribbled, rather."