Before Gerald could answer the very unpleasant question, there came a sound which caused both men's hearts to cease beating for a moment, the one with hope, the other with fear.

For it was a loud hammering on the front door, and an authoritative voice crying:

"Open instantly, or we break in."

Looking at the door, the lawyer saw through the ground glass a round disk of light, such as a bull's-eye lantern throws, and then silhouetted a helmet—a policeman's helmet.

Loide stood in the passageway with a blanched face—irresolute—for a moment. There was not time to be so longer.

Then he rushed to the back door, and disappeared down the steps into the darkness.

His movements were quickened by the sound of breaking glass. A truncheon had shattered one of the panels in the door, and a coat sleeve, with a striped band round it, was thrust through the hole in the glass.

There was a hand in the sleeve, a hand feeling around for the catch, a policeman's hand.

The hand caught the catch, and presently the door opened.

Three men in uniform stood on the steps, a sergeant and two constables. They paused a moment listening, and then entered.

"Be careful," said the sergeant. "Throw your light ahead of you. Hullo! What's this?"

He was referring to the open trap which yawned at his feet.

He cast the light of his lantern down the hole, and a voice came up, saying:

"The police! Thank God!"

"Wasn't a hoax then, after all," said the sergeant grimly. "Are you all right?"

"Yes," came the voice; "all right now you have arrived. Had you been five minutes later you would have had a dead man to carry out."

"Who's the would-be murderer?"

"Escaped the back way as you entered the front. I heard him run down the steps."

"Jim, Jack, quick; scour the back, and see what you can find."

The men found nothing. They returned.

"He knew the lay of the land better than we did," said the sergeant; and then stooping over the opening in the floor, he continued, "How are we going to get you out of this?"

"That's the question which was put to me five minutes ago, only it was proposed to bring me out dead, not alive."

"Shall I try and borrow a ladder, sergeant?" inquired one of the men. "Or a pair of steps would do."

"Where the devil are you going to borrow such a thing at midnight? Slip off your belts. Here's mine; buckle them together. That's it."

He leaned over the hole, and lowered the length of leather.

"Just wrap the end round one wrist," he called out to the man below, "and hold on with the other hand. Got it? Now, Jim, Jack, grip this. Stand on the corner there and pull all together."

The long, strong pull of the three men brought Gerald's head above the hole.

"Catch hold of the side with your free hand," called out the sergeant; "that will relieve the weight. That's it. Stoop down, Jack, and catch his arms. There."

In another moment Gerald formed one of the four panting men in the passage.

"And now," inquired the sergeant, "what's the meaning of this little game? How did you come to get down there?"

"First tell me," inquired Gerald, "how you came to arrive in the very nick of time?"

"Well, your note—ingenious idea that—round the cat's neck, was noticed by the cat's owner. At first she thought it was a hoax, but ultimately she put on a bonnet and shawl, and came with it to the police station."

"Good woman!"

"It seemed a funny sort of story to find tied to a cat, and at first we shared in the belief that it was a hoax. We probably should have treated it so—for you don't find this kind of thing happening except in books, you know—but one of our men who was standing in the office had reported that two vans had cleared the furniture away from The Elms during the evening.

"I think that decided us. If it had not been for the fact that it was an empty house—empty houses form the backgrounds of a lot of crimes, you know—I don't think we should have taken notice of it."

"That would have been pleasant."

"You can't conceive how the police are hoaxed, or you wouldn't wonder. We seem to be fair game for the practical joker. But now, tell us, how did you get down that hole?"

"It's a long story," said Gerald, who for obvious reasons could not tell the true one. "I was lured here presumably by a madman, walked into that trap, and when you were knocking at the door, the fellow was standing over me with a pistol. He had dug a grave in the back garden—you can see it for yourself—and was intending to bury me in it."

"Who was it?"

"The man who lived here—Mr. Loide, the lawyer. I was his clerk. He sent for me to come here to-night, and I came down by train. When I got here—well, the man was mad; there can be no doubt of it."

"Just give me his description," said the sergeant; "we don't want madmen rambling about a quiet little place like Wimbledon. The sooner we spot the old gentleman the better. He seems to be shaping himself for a strait jacket."

"A quiet five minutes with him," replied Gerald viciously, as he clenched his fist, "would, I think, result in his being one of the sanest men in the country. I shouldn't forget in the interview that he tried to murder me."

"You don't want to take the law into your own hands. That's what we are around for. Now, give me his description."

Gerald gave it. Then the sergeant said:

"Your own name and address."

Gerald gave them.

While the sergeant had been eliciting these particulars, and writing an account of the affair, his men had searched the house from top to bottom, and reported absolute emptiness.

"Now I think we have done here. Better let us take the key," said the sergeant; "we'll go over the place again to-morrow. If he's as mad as you say he is, he's likely to come back. We may be able to clap hands on him if we keep watch."

The street door was locked, and the four men made their way to the high road.

"I would give something for a drink of brandy," said Gerald.

"I fear you are not in such dire distress as to warrant my knocking up a licensed victualer," replied the sergeant. "How would a cup of hot cocoa fit you? There's a stall at the corner."

Gerald sampled it, and found it grateful and comforting.

"Now, about sleeping. Will you come on to the station? We can give you a pitch there on a rug till the morning."

Gerald thanked them and walked to the police station. The next morning he was up betimes, and caught an early train back to London.

His astonished landlady let him in, and opined with a shaking head that there was only one end for young men who stopped out all night.

Gerald did not want to hear what the termination was, but made his way up-stairs.

In his own room he lay on his bed and slept. He had not found the bench at the police station of a soporific kind.

After the excitement of the preceding evening, he needed sleep, and he took his fill of it.

He did not awake till eleven o'clock; then he had breakfast, and mapped out his plans for the day.

He rehearsed his coming interview with the dentist—he did not suppose it would matter being an hour or so late—what he should say, what he should do, and then went out.

His landlady sarcastically inquired as he passed whether he thought he should sleep at home that night, and he answered by banging the door.

He made his way to Finsbury Circus, and entered the building in which the dentist had rooms. Sawyer opened the door.

"Is Mr. Lennox in?"

"Yessir; will you come inside? What name shall I say, sir?"

"Brown—John Brown."

Then Gerald sat down and waited while the boy took his name in to his employer.

"Am I going to draw a prize or a blank," he muttered. "Am I coming out of this interview with the notes in sight, or failure?"

His interview with the dentist told him.