“What do you make of that?”

“Heaven knows!” groaned Dick.

The study door was closed, and he had pulled across a dark curtain which had been hung that day for the purpose.

“I suppose I’d better get out, though I don’t suppose I shall find anything.”

“Wait until I’ve had the remainder of your coffee and I’ll come with you,” said Puttler. “No, Mr Alford, I never felt less like sleep. We shall have daylight in a couple of hours. Wait.”

He turned down the oil lamp which had been requisitioned from the kitchen, blew down the glass chimney and the room was in darkness.

“Now you can pull open those curtains and go out,” he said, “if that is your way.”

Dick moved the curtains slightly and looked out. The world lay peaceful, silent, in the pallid light of the moon, and as he opened the door, the sweet scent of the earth and the cold morn greeted him fragrantly.

His foot was raised to step across the threshold when Puttler’s big hand closed round his arm.

“Wait,” he whispered again.

Dick stood motionless.

“I see nothing,” he said in the same tone.

Still Puttler held him, his head bent, listening.

“All right,” he said, released his grip and stepped out on to the little terrace before Dick.

He gave a swift glance left and right.

“What was it?” asked Dick, in surprise.

“Somebody breathing,” was Puttler’s astonishing reply. “You won’t believe that I could hear a man breathing a dozen yards away, but I can. It’s one of my many animal qualities.”

He took a little run, cleared the gravel path in a bound and went noiselessly along the grass to the left. Presently Dick saw him returning at a jog-trot. The detective went past him and disappeared round the wing of the block. In a few minutes he returned.

“Hearing and scent are my two qualities. Can you smell anything?”

Dick sniffed the morning air.

“No,” he confessed.

“Come along with me.”

This time he walked softly across the path, explaining that he was afraid of waking the girls, who slept almost immediately above them.

They went to the end of the wing, and then the sergeant halted.

“Now do you smell anything?” he asked.

Dick sniffed again. There was a sweet odour in the air, the scent of some exotic flower that seemed familiar to him.

“Does anybody in this house smoke scented cigarettes?” asked the detective, and Dick went suddenly cold.

“Harry!”

“Your brother, eh?” Puttler’s deep-set eyes surveyed him in the half-light. “That doesn’t necessarily mean that he is smoking them. Where were they kept?”

“In the library as a rule.”

Puttler began searching the ground with the aid of his lamp. He had not gone far before he saw something and picked it up. It was a half-smoked cigarette with a rose-leaf tip.