“One moment!” interposed Linckes. “Can you remember what the man who fell against you looked like?”

“Just—just ordinary,” answered the unhappy secretary. “He was middle-aged, I think, but I won’t swear to it.”

“I see. Thank you! Winthrop, I won’t stay to dinner, if you’ll excuse me. I’ll get right on to this at once.”

Winthrop nodded.

VI.

IT was close on eleven o’clock that same evening, and Arlington Street was very quiet. One or two people passed down the road, and presently someone left Winthrop’s house and went away in a large limousine. Several people had visited Sir Charles that evening, and he himself had returned from Caryu’s house shortly after eight.

For some time after the last visitor had departed there was silence in the street, and then the chunk-chunk of a London taxi made itself heard, and in a few moments a car drew up outside No. 10. A man in an overcoat and opera hat got out, paid the driver, and mounted the steps to the front door. He pressed the bell, and stood waiting to be admitted. He was a medium-sized man, inclined to stoutness, and with a short, grizzled beard. The butler opened the door.

“Is Sir Charles in?” asked the newcomer. His voice was rather hoarse and guttural.

“Yes, sir. But I don’t think he’s seeing anyone else today.”

“Would you ask him if he will give me a moment?”

The man handed John a card. The butler read it.

“Oh, Mr. Knowles, sir! I beg your pardon! Will you come in while I see if Sir Charles is still up?”

Knowles entered the house, and the door closed again.

From the shadowy depths of the area two men rose stealthily, and crept up the steps to the street.

“Got him!” Linckes whispered. “Your revolver ready, Tomlins?”

His companion nodded.

“Yes, it is. Wish I knew what you’re about.”

“You soon will know," said Linckes grimly. “Your men are prepared?”

“Inspector Gregory’s at the back of the house, Mr. Linckes, and Inspector Marks is just down the road. He’ll come up to the house with Sergeant O’Hara as soon we get in.”

“All right. Don’t forget that all you’ve got to do is to follow me and to do as I say instantly.”

“No, sir. Carry on!”

Linckes ran lightly up the steps of the house and rang the bell. After a short pause the door was opened.

“John, is Sir Charles up?”

“Yes, sir. Oh, is it you, sir? Come in!”

Linckes walked into the hall, followed by the other detective. John looked at Tomlins surprisedly.

“Sir Charles is engaged just at the moment, sir. But if you’ll wait—”

“Oh, is he? We’ll just wait here, then. Don’t bother to stay, John.”

He turned to Tomlins.

“The library is at the bottom of this passage. It’ll be locked, and we shall wait in absolute silence outside. There are two men in the room, and when they come out you are to cover Sir Charles Winthrop. Leave the other to me. See?”