"Then I'll spend the time writing the History of Department Z., sir,"

was the quiet reply. The two men went out, and Mr. Llewellyn John rang for his secretary.

"You have rather----" began Colonel Walton, but he stopped short. Sage suddenly knocked him roughly with his elbow.

"I have never seen the Mons Star," he said. "Can we go round by Whitehall? The Horse Guards sentries, I believe, wear it."

The two men had reached the top of the steps leading down into St.

James's Park. Without a moment's pause Sage turned quickly, and nearly cannoned into a pretty and stylishly dressed girl, who was walking close behind them. He lifted his hat and apologised, and he and Colonel Walton pa.s.sed up Downing Street into Whitehall. For the rest of the walk back to St. James's Square, Sage chatted about medals.

Seated once more one on either side of Colonel Walton's table, Sage proceeded to light his pipe.

"Clever, wasn't it?" he asked. "She's fairly new, too."

"Who was she?"

"Vera Ellerton, employed as a Temporary Ministry typist," Sage replied drily.

"So that was it," remarked Colonel Walton, cutting the end of a cigar with great deliberation.

"She was following us on the chance of catching any odd remarks that might be useful. On the way back here two others picked us up on the relay system."

"Do you think she knew who we were?" enquired Colonel Walton.

"No, just an off chance. We were callers on the Skipper, and might let something drop. It's a regular thing, picking up the callers, generally when they've got some distance away though."

"They must have learned quite a deal about numismatics," said Colonel Walton drily.

"A const.i.tutional government is a great obstacle to an efficient Secret Service, it imposes limitations," remarked Sage regretfully.

Colonel Walton looked across in the act of lighting his cigar.

"There are six hundred and seventy of them at Westminster. In war-time we require a system of the _lettre-de-cachet_. And now," said Sage, rising, "I think I'll get a couple of hours' sleep, I've been pretty busy. By the way," he said, with his hand upon the door-handle, "I think we might get the papers of that fellow on the Bergen boat, also a photograph, clothing, and full details of his appearance."

Colonel Walton nodded and Malcolm Sage took his departure.

II

"It's curious."

Malcolm Sage was seated at his table carefully studying several sheets of buff-coloured paper fastened together in the top left-hand corner with thin green cord. In a tray beside him lay a number of similar doc.u.ments.

He glanced across at a small man with a dark moustache and determined chin sitting opposite. The man made a movement as if to speak, then apparently thinking better of it, remained silent.

"How many false calls did you say?" enquired Sage.

"Nine in five days, sir," was the response.

Malcolm Sage nodded his head several times, his eyes still fixed on the papers before him.

One of his first acts on being appointed to Department Z. was to give instructions, through the proper channels, that all telephone-operators were to be warned to report to their supervisors anything that struck them as unusual, no matter how trivial the incident might appear, carefully noting the numbers of the subscribers whose messages seemed out of the ordinary. This was quite apart from the special staff detailed to tap conversations, particularly call-box conversations throughout the Kingdom.

A bright young operator at the Streatham Exchange, coveting the reward of five pounds offered for any really useful information, had called attention to the curious fact that Mr. Montagu Naylor, of "The Cedars,"

Apthorpe Road, was constantly receiving wrong calls.

This operator's report had been considered of sufficient importance to send to Department Z. Instructions had been given for a complete record to be kept of all Mr. Montagu Naylor's calls, in-coming and out-going. The first thing that struck Sage as significant was that all these false calls were made from public call-boxes. He gave instructions that at the Streatham Exchange they were to enquire of the exchanges from which the calls had come if any complaint had been made by those getting wrong numbers. The result showed that quite a number of people seemed content to pay threepence to be told that they were on to the wrong subscriber.

"What do you make of it, Thompson?" Malcolm Sage looked up in that sudden way of his, which many found so disconcerting.

Thompson shook his head. "I've had enquiries made at all the places given, and they seem quite all right, sir," was his reply. "It's funny," he added after a pause. "It began with short streets and small numbers, and then gradually took in the larger thoroughfares with bigger numbers."

"The calls have always come through in the same way?" queried Malcolm Sage. "First the number and then the street and no mention of the exchange."

"Yes, sir," was the response. "It's a bit of a puzzle," he added.

Malcolm Sage nodded. For some minutes they sat in silence, Sage staring with expressionless face at the papers before him. Suddenly with a swift movement he pushed them over towards Thompson.

"Get out a list of the whole range of numbers immediately, and bring it to me as soon as you can. Tell them to get me through to Smart at the Streatham Exchange."

"Very good, sir;" and the man took his departure.

A minute later the telephone bell rang.

Malcolm Sage took up the receiver. "That you, Smart?" he enquired, "re Z.18, in future transcribe figures in words exactly as spoken, thus double-one-three, one-hundred-and-thirteen, or one-one-three, as the case may be." He jammed the receiver back again on to the rest, and proceeded to gaze fixedly at the finger-nails of his left hand.

A quarter of an hour later Special Service Officer Thompson entered with a long list of figures, which he handed to Malcolm Sage.

"You've hit it, Thompson," said Sage, glancing swiftly down the list.

"Have I, sir?" said Thompson, not quite sure what it was he was supposed to have hit.

"They are----"

At that moment the telephone bell rang. Malcolm Sage put the receiver to his ear.

"Yes, Malcolm Sage, speaking," he said. There was a pause. "Yes."

Another pause. "Good, continue to record in that manner;" and once more he replaced the receiver.

"Vanity, Thompson, is at the root of all error."

"Yes, sir, said Thompson dutifully.

"Those figures," continued Sage, "are times, not numbers."

With a quick indrawing of breath, which with Thompson always indicated excitement, he reached across for the list, his eyes glinting.

"That was Smart on the telephone, another call just come through, three-twenty Oxford Street, not three-two-o, but three-twenty. Make a note of it."

Thompson produced a note-book and hastily scribbled a memorandum.