“Well, my boy, what are you doing here?” he asked.

“I cannot answer get,” Quest replied, in broken English.  “Ten minutes already have I wasted.  I have knocked at all the doors.”

French smiled.

“You can hop it, Dutchie,” he advised.  “By-the-bye, when was that order for vegetables given?” he added, frowning for a moment.

“It is three times a week the same,” Quest explained, whipping the cloth from the basket.  “No word has been sent to alter anything.”

The Inspector pushed him hurriedly in the direction of the street.

“You run along home,” he said, “and tell your master that he had better leave off delivering goods here for the present.”

Quest went off, grumbling.  He walked with the peculiar waddle affected by young Dutchmen of a certain class, and was soon out of sight round the corner of the street.  French opened the door with a masterkey and secured it carefully, leaving one of his men to guard it.  He searched the rooms on the ground floor and finally ascended to Quest’s study.  The Professor was still enjoying his cigar.

“Say, where’s Quest?” the Inspector asked promptly.

“Have you let him out already?” the Professor replied, in a tone of mild surprise.  “I thought he was in the Tombs prison.”

The Inspector pressed on without answering.  Every room in the house was ransacked.  Presently he came back to the room where the Professor was still sitting.  His usually good-humoured face was a little clouded.

“Professor,” he began—­“What’s that, Miles?”

A plain-clothes man from the street had come hurrying into the room.

“Say, Mr. French,” he reported, “our fellows have got hold of a newsie down in the street, who was coming along way round the back and saw two men enter this house by the side entrance, half-an-hour ago.  One he described exactly as the Professor here.  The other, without a doubt, was Quest.”

French turned swiftly towards the Professor.

“You hear what this man says?” he exclaimed.  “Mr. Ashleigh, you’re fooling me!  You entered this house with Sanford Quest.  You must tell us where he is hiding.”

The Professor knocked the ash from his cigar and replaced it in his mouth.  His clasped hands rested in front of him.  There was a twinkle of something almost like mirth in his eyes as he glanced up at the Inspector.

“Mr. French,” he said, “Mr. Sanford Quest is my friend.  I am here in charge of his house.  Believing as I do that his arrest was an egregious blunder, I shall say or do nothing likely to afford you any information.”

French turned impatiently away.  Suddenly a light broke in upon him, he rushed towards the door.

“That damned Dutchie!” he exclaimed.

The Professor smiled benignly.

CHAPTER VII

THE UNSEEN TERROR