“You’re certainly a bit morose,” admitted Linckes. “What a mercurial sort of chap you are! A fortnight ago you were perfectly cheerful, and then you were suddenly plunged in despair!”

“Can’t help it. Made that way.” Winthrop picked up his pen, and started to address an envelope. “Oh, now the beastly pen won’t write! Damn! I hate quills!”

“Then why use them?”

“Heaven knows! I used to like them awfully. Yes, John?”

The butler had entered the room.

“Mr. Knowles to see you, sir.”

Winthrop’s brow cleared as if by magic.

“Knowles? Show him in, will you? I say Linckes, do you mind if I interview this man? I won’t be many minutes.”

Linckes rose at once.

“Rather not! I’ll clear out for a bit, shall I? Can you give me a little time when you’ve finished? There are one or two questions I want to ask you.”

“Of course! Show Mr. Linckes into the drawing-room, please, John.”

Linckes went to the door just as Winthrop’s visitor entered. As he went out Linckes cast him a passing glance, and noted that he was an elderly man with grizzled black hair and a short beard and moustache. He bowed slightly, received a pleasant smile in return, which vaguely reminded him of someone, and went out.

He had not to wait long. Presently, from the drawing-room window, he saw Knowles descend the steps of the house and hail a passing taxi. As the vehicle drew up beside the kerb, he turned and saw Linckes. He nodded slightly, smiling, and after speaking to the taxi-driver got briskly into the cab. He let down the window, and as the taxi moved forward looked up at Linckes with a strangely mocking expression in his eyes.

Then the butler came to tell Linckes that Sir Charles was at liberty.

Winthrop was standing with his back to the fire when Linckes came in, smoking, and he greeted the detective with his old, sunny smile.

“I say, I’m awfully sorry to have turfed you out like that!” he exclaimed. “My time’s not my own, you know. What do you want to ask the especially? Didn’t you say there were one or two questions?”

Something about him was puzzling Linckes. The frown had quite disappeared from Winthrop’s face; the nervous, irritable movements had left him. He was smiling in his own peculiarly charming fashion, and as he looked at Linckes he sent two long columns of smoke down through his nose.

“Every track turns out to be the wrong one,” Linckes answered bitterly. “I begin to think we shall never get to the bottom of it all.”

Winthrop went to his desk and picked up the despised quill. He held it poised, smiling at Linckes.

“Oh, come! Don’t lose hope, Linckes! Something must leak out soon.”

Linckes stared at him.

“Well, I like that! Only half an hour ago you were groaning that nothing would ever be discovered!”

“Yes, but that was half an hour ago,” Winthrop, explained. “I’ve taken a turn for the better since then.”