do what you like," answered the Sub.

"Very good. To-morrow I take out a summons. If between the present time and the date of the hearing you decide to accept my terms I will immediately withdraw the summons and your dog's life will be saved. Good evening!"

CHAPTER II

An Ultimatum

Confronted with the mysterious problem Sub-Lieutenant Fordyce made his way to a secluded part of the sea-front. With a true sailor's instinct he paced up and down, debating with himself as to the course of action he should pursue.

If only he had a witness to the conversation. He racked his brains to formulate a scheme whereby he could discuss the matter again with Councillor Mindiggle, this time with a third person unseen but within earshot. Failing that there was little use in reporting the matter. As the fellow said, it was one man's word against another's, and the charge would appear so preposterous that it would stand no possible chance of being substantiated.

For similar reasons he dismissed the idea that he should report the case to his skipper, the Hon. Derek Stockdale, Lieutenant-Commander of R19. Mindiggle's statement that the Sub had informed him of the vessel's date of departure and destination would be an awkward factor in the matter.

So, rightly or wrongly, Noel Fordyce resolved to keep secret the interview with Councillor Mindiggle, at least for a time. Meanwhile he would fight to the bitter end to save Flirt from the lethal chamber.

Having shut the front door on his caller, Councillor Mindiggle returned to his study. As far as the rest of his household was concerned he was free from interruption. He had no wife; his housekeeper was stone deaf; the servant who had shown Fordyce into the room was going out for the evening.

It would have been a great surprise to Fordyce if he had known that there had been a third person within earshot, but such was a fact. Unlocking a door leading into an inner room Mindiggle released a man who, although he looked an Englishman, spoke in Russian.

"Don't you think, comrade, that you were much too rash?" he asked anxiously.

"Not at all, Boris Platoff," replied Mindiggle coolly. "On the contrary, I have hopes that we shall be relieved of a considerable amount of bother and danger. The diamonds will be in Petrograd before the great day. That young man will consent to my terms. It's wonderful what a hold one has over an Englishman who owns a favourite dog. Inform the police—bah! He would not dare risk the ridicule his action would bring upon him. Those diamonds will go in the submarine, you mark my words."

"Let us hope so," rejoined Platoff. "Then, either they will reach Comrade Klostivitch or else it will be an end to R19. It depends largely on the temperature in the Baltic, eh?"

Both men laughed softly.

"Supposing," continued the Russian—"Supposing—and we must consider possibilities—this English officer takes the diamonds and then hands them over to the authorities?"

"I'll have to take the risk of being convicted as a smuggler, comrade," replied Mindiggle.

"But if they are subjected to a test?"

"They will discover nothing. I defy the efforts of the world's laboratories to analyse the stuff," declared Mindiggle. "Acid, heat —nothing will avail."

"Except cold," added Boris Platoff.

"Then it will be what the ancient Egyptians call Nirvana," said the other grimly.

Boris Platoff was a Leninist, a member of the ultra-extremist party in Russia. Having, under German influence, taken a prominent part in wrecking the Russian Empire as a fighting-machine, he was doing his best to supplant the Kerensky regime by one of red-hot anarchy. While on a mission to the Russian Anarchist colony in London he had been given an introduction to a member of the World's Workers—a revolutionary society the object of which was the social democracy of every nation under the sun. This member's name was simply given as Comrade Ivan, known outside the brotherhood as Mr. John Mindiggle.

While posing both as an Englishman and a Russian, John Mindiggle was neither. He was a German—a Secret Service agent—whose work was entirely for the futherance of Kaiserism. During twenty years of practically continuous residence in Great Britain Ernst von Verbrennungsraum had been working unostentatiously, yet deliberately, for the Fatherland, for the day when Germany would become the mistress of the World and when freedom would be denied to all other nations large or small.

Von Verbrennungsraum's chance came when Russia took the suicidal step of exchanging the yoke of Czardom for that of unbridled "liberty". The first revolution that resulted in the abdication of the Czar Nicholas was a step in the right direction so far as Germany was concerned, but it was not far enough. The new republic still maintained an army on its Austro-German frontier—an army in which bravery and cowardice existed cheek by jowl. Utter internal chaos was what was desired in order to remove a menace to Germany's eastern frontier and thus enable her to throw thousands of troops into other sectors of battle.

To compass the downfall of the Kerensky regime the anarchists were to resort to a favourite device—explosives. In a secret laboratory was manipulated a new and extremely powerful chemical, which, in its final state, resembled, and could hardly be distinguished from, cut diamonds. It was a sample of this diabolical stuff that Mindiggle was in hopes of sending to Petrograd through the agency of Noel Fordyce.

Impossible to detonate by combustion, friction, or the application of heat, the explosive was perfectly safe to handle until the temperature fell below -5° C. The moment the mercury dropped to that point the explosive would simultaneously and spontaneously act.

In his attempt to induce Fordyce to convey the "diamonds" to Russia the German agent was employing a double-barrelled weapon. If the stuff did get to Petrograd well and good. If, on the other hand, the temperature on board the submarine should fall below -5° C. while running awash towards the port of Cronstadt, it meant utter annihilation to R19 and terrific damage to everything within a mile of the source of the explosion.

And, confident in his ability to make use of Flirt as the deciding factor, von Verbrennungsraum duly applied for and obtained a summons against Noel Fordyce.

CHAPTER III

The Sub's Stratagem

Ernst von Verbrennungsraum had not taken into account one of Noel Fordyce's characteristics—that of grim, almost obstinate determination. Under the mistaken impression that, for the sake of his pet, the Sub would agree to his terms, the Secret Service agent applied for and obtained a summons.

"I'll fight him while I have a penny left to call my own," declared Fordyce, and with this laudable intention he engaged the best solicitor in Otherport.

The German could not now back out without loss of dignity as a respected member of the Otherport Town Council. He had to proceed with the case, unless Fordyce capitulated.

The morning of the day fixed for the hearing came round. Noel Fordyce, in uniform, made his way towards the Town Hall. Flirt was safely under lock and key. An hour would decide whether she was to live or die.

The young officer had not reached the end of the road when an Irish terrier bounded up to him. It was Nell, Colonel Richardson's animal and Flirt's mother, a quiet, affectionate and absolutely inoffensive little beast. Flirt did not inherit her one bad trait from her mother.

"Go back, Nell," ordered Noel. "Home! I can't take you for a stroll this morning."

The dog, for once in a way, took no notice of the command. After several vain attempts to send her back, Fordyce gave it up as a bad job, and with Nell close at his heels he entered the Town Hall.