The position was very grave. If Fedoroff's information was correct--and d.i.c.k saw no reason to doubt it--here was a desperate scoundrel lurking in England armed with an aeroplane of unknown design and power, and in possession of a terrible secret which, unless his career was brought to an end, threatened the entire population of the country. But where was he hiding, and, above all, where was his machine? Could it possibly be hidden, d.i.c.k wondered, in the very heart of London? The idea was almost incredible, but d.i.c.k knew Barakoff's undoubted genius and his amazing daring.

A remarkable feature of Yvette's personality was her wonderful influence over children. They seemed literally to worship her. She would get into conversation with the half-tamed _gamins_ of the streets and in a few hours they would be her devoted slaves. She now proceeded to enlist the ragged battalions of Soho in a fashion that caused Buckhurst much amus.e.m.e.nt.

"Find out for me all the hunchbacked men you can," was all the instructions she gave them.

"But, mademoiselle," said Inspector Buckhurst, "it will be the talk of Soho, and our man if he is there will slip away."

Yvette was unmoved.

"Just think a minute," she said. "Who can go about all day and all night without being suspected? The children. Who can go into dens where your men hardly dare to venture? The children. Who know all the hidden haunts of which your men are utterly ignorant? The children.

And finally, who are the most secretive people in the world? Again the children. Do not fear, Monsieur Buckhurst, they will not talk except among themselves, and that will do no harm."

Buckhurst was far from satisfied, but he had gained such a respect for Yvette that he did not venture to override her. At the same time, he told her plainly that he should keep his own men busy. Yvette only laughed.

During the next forty-eight hours dozens of hunchbacked men were reported. Many of them were people whom not even the police knew. They were, of course, mostly harmless, but Buckhurst opened his eyes when one of them proved to be a notorious forger for whom the police had been looking for some months, and who had all the time been hidden under their very noses! Buckhurst began to feel a growing respect for the amazing French girl, who had beaten his smartest detectives on their own ground. But, unfortunately, none of the hunchbacks was the man they wanted, and at last they began to suspect that Fedoroff's information was at fault.

Then came a dramatic surprise. One of Yvette's small a.s.sistants, a sharp little Polish Jew boy, came to her with a strange story. He had been wandering about the night before and had seen a hunchbacked man let himself out of the side door of a big building half-way between Greek Street and War dour Street. The man had walked a considerable distance in a northerly direction into a part of London the boy did not know at all, and had entered an unoccupied house, stayed a few minutes, and come out again. The lad had shadowed him all the way, and had followed him homewards, until he again entered the building in Soho.

d.i.c.k, Jules, and Yvette turned out at once. The boy pointed out the building to them. It was a tall structure which dominated all the others in the vicinity. It was apparently a big shop with storerooms above. On the facia over the windows was the name "Marcel Deloitte, Antique Furniture." There was nothing to indicate that it differed in the slightest degree from dozens of other shops and buildings in the neighbourhood. Yet d.i.c.k felt suspicious.

"We can do nothing till I get the Mohawk handy," said d.i.c.k. "I will bring her down to-night."

And he paused.

"I wish you would keep out of this, Yvette," he went on wistfully. "It is going to be very dangerous, I am convinced." The French girl was growing very dear to him, and he shuddered at the idea of her being mixed up in the coming struggle with a desperado of Barakoff's type.

But Yvette shook her head.

"I'm in this to the finish, d.i.c.k," was all she said in her pretty broken English, and d.i.c.k knew he could not move her. But he was full of fear.

That afternoon another explosion of the pale-violet vapour occurred in North London not far from Finsbury Park Station. d.i.c.k rushed to the spot with the boy who had followed the hunchbacked man, and the lad recognised the place without hesitation. The house destroyed was, he was confident, the one the hunchback had entered the night before.

Barakoff was located at last! But how was he to be captured? The problem was not so easy.

It was vital that, if possible, he should be taken alive. They knew what would follow the explosion at Finsbury Park, and there was a chance at least that if Barakoff were captured the secret of the disease, and possibly the antidote, might be wrung from him. If they could succeed in that hundreds of lives would be saved.

Together the three worked out a careful plan for the _coup_ they intended to bring off next morning.

Very early a dozen street arabs were playing innocently close to the two entrances of the mysterious building. They were chosen specimens of Yvette's band of ragam.u.f.fin detectives, and she knew that if Barakoff tried to escape he would have no chance of eluding their keen eyes. All the approaches were blocked by detectives, but Yvette insisted that none should approach the house itself. It was essential to the success of their plan that Barakoff's suspicions should not be aroused.

From the roof of a big building half a mile away, d.i.c.k made a careful examination of what he was now convinced was Barakoff's hiding-place.

But he could see little. The roof was flat, but it was surrounded by a parapet practically breast high. There was obviously plenty of room to conceal a small aeroplane, but d.i.c.k could see nothing.

d.i.c.k and Buckhurst together saw the proprietor of the building from which d.i.c.k had made his observations. He readily consented to d.i.c.k's plan, and towards evening placed a trusty commissionaire at the foot of the flight of steps leading to the roof with instructions that no one was to pa.s.s on any account whatever. Soon after dark the Mohawk dropped silently on to the flat roof. They were ready now to catch their bird!

In the morning Yvette, under the pretence of wishing to buy some old furniture, entered the shop. So far as she could see there was nothing suspicious. There was a manager, evidently a Russian, and two a.s.sistants.

Asking for a Jacobean chest which she did not see in the shop, Yvette was at length invited to the upper floors. These she found to be full of furniture.

Climbing the stairs to the third floor, accompanied by the manager, Yvette found herself in a large room divided in the centre by a wall, and with a door in the middle. Opening this door the manager bowed to her to precede him, and Yvette, quite unsuspectingly, obeyed. Next second the door crashed to, and she heard a key turn in the lock. She was trapped!

Before she could recover from her astonishment there was a rush of feet behind her, and she found herself seized in a grip which, as she at once recognised, it was far beyond her strength to shake off. She struggled frantically, but in vain. She was hopelessly overpowered and swiftly bound, and laid, gagged and helpless, on a sofa in the corner of the room. Then for the first time she caught sight of her captor. She recognised him at once. It was Barakoff himself! _Worse still, he knew her_!

The man was mad with rage, his face convulsed and his eyes blazing with fury.

"So, Mademoiselle Pasquet! We meet at last!" he snarled, stooping over her until his face was within a foot of her own and she could feel his hot breath upon her cheek. "But it is for the first--and last time!"

Accustomed as she was to danger in many forms, Yvette could not repress a shudder. In the power of a ruffian like Barakoff! She knew, of course, that at any moment Jules might become suspicious of her long absence and come in search of her. But how long would he be and what might happen in the meantime?

Barakoff set swiftly to work and fixed inside the doors heavy bars which, as Yvette realised with a sinking heart, would effectually shut out anyone trying to gain admittance, until either the door was reduced to splinters or a hole was knocked in the wall. Then he picked her up without an effort and carried her into the adjoining room. This, to Yvette's intense surprise, was elaborately fitted up as a chemical laboratory, with all kinds of strange instruments and apparatus. It was evident that it had long been used for this purpose.

With an evil sneer Barakoff took from a cupboard what Yvette had no difficulty in recognising as one of the poison bombs! This he placed on a table and attached to it a short length of fuse. Then he began to busy himself with what seemed to be preparations for leaving, packing a few articles of clothing in a small bag and laying it down with a heavy coat beside it.

"When night comes, I go," he said. "But you--you will remain. But I shall leave you in good company, mademoiselle," and he pointed to the deadly bomb. "You will not feel dull. And after I am gone you will die--very slowly--of the twisted arms."

For a few minutes the miscreant sat silent, smoking a cigarette and regarding Yvette with a look of triumph she found even harder to bear than the consciousness of her terrible danger.

Jules, on watch below, had at length become uneasy. He entered the shop and asked one of the a.s.sistants if the lady was still there.

"Yes," replied the fellow readily, "she is upstairs with the manager looking at some furniture."

Jules, his hand on his pistol in his pocket, and feeling strangely uneasy, started up the stairs. There was no one in the building. What could have become of Yvette and the manager?

On the third floor he noticed the door through which Yvette had gone.

He seized the handle and tried to open it. But the door was locked and there was no key.

Not daring to raise an alarm for fear of the consequences to Yvette, Jules hastened down the stairs, and signalled to one of the Scotland Yard men. In a low voice Jules told him what had happened.

"We must be ready to break down that door at once," he said.

With swift efficiency help was summoned, including a couple of men of the salvage corps, armed with powerful axes which would make short work of any ordinary door.

While the shop a.s.sistants were kept under surveillance, Jules and his helpers mounted to the third floor. They tried the door, and knocked.

There was no reply, but inside they heard the hasty scurry of feet.

"Break it down," said Inspector Buckhurst, who had been one of the first to arrive.

The salvage men sprang forward, and one on each side of the door began a furious attack with their axes.

Instantly a shot rang out. Splinters flew in showers, but the door, heavily barred and plated with iron, for a time defied all their efforts. At last it gave way, and headed by Jules the police party rushed in.

Their first discovery was Yvette, lying unconscious and bleeding profusely from a wound in the shoulder. Barakoff had fired at her as he hurried from the room when the thunderous attack on the door began. But in his blind haste his aim had been bad, even at such short range, and she escaped with comparatively slight injury.

But where was Barakoff?

Rushing out on to the flat roof Jules looked hurriedly round. To the southward a queer-looking aeroplane was just vanishing into the thin mist. But behind it, going "all out," sped the Mohawk in furious pursuit. d.i.c.k Manton was taking a hand in the game of which he was a master! There could be but one end to that, Jules thought, with a sigh of relief as he turned to look after Yvette.

She was recovering consciousness and they were just about to carry her out, when one of the policemen with a loud cry dashed to the table. He had caught sight of a thin thread of smoke rising from the fuse of the bomb!