"No," said Gaston, "it is absolutely essential that you shall remain in the prison. But I think I can see a way."

He crossed the room to an old-fashioned bureau and produced from a drawer what looked like a heavy short-barrelled pistol.

"Gas!" he said laconically, "fire that at a man's face within five yards and he will drop like a log. It holds four shots and makes no noise.

If Mademoiselle can get this she can knock out the two men at the lodge and easily slip out. You can bring her straight here, and we can hide her until she can get away."

"She cannot hide that in her cell," said Pierre, "but I can hide it in the courtyard. Write her a letter telling her exactly what to do and where the pistol will be. I can slip into her cell a skeleton key which will open the door and also the door at the bottom of the steps. But you must manage the rest; I cannot do any more. She must get out immediately after the last visit of the warders at nine o'clock."

"Thanks very much, Pierre," said Jules. "I can see no other way, and at all costs we must try to get her out. Neither my sister nor myself will ever forget."

Speedily a letter was written which gave Yvette full details of what was proposed, and Pierre was about to leave when Jules asked him if he had heard anything of the secret aeroplane.

Pierre shook his head.

"There are a lot of privately owned aeroplanes about here," he said, "but I don't know anything more than that. I have seen the one you refer to going up at night--the house is in plain view from my room on the first floor of the prison--but I never heard there was any secret about it, and there are so many aeroplanes about that no one takes any notice of them."

Jules told him all they had found out, and of their suspicions, and found Pierre was able to give them valuable information.

The aeroplane shed, he told them, was just where Yvette had located it.

Above it--and this was important--were some rooms which were used, apparently, as offices.

"I have often," said Pierre, "seen a man come from the offices with what looked like plans, make examination and measurements of the machine, and then go back. But I never took much notice; I had no reason to."

Pierre left, taking with him the letter to Yvette. For an hour Jules and Gaston discussed the situation.

"We must get her out to-morrow," declared Gaston, "or else they may take her away and we shall not be able to find out where she is. Manton ought to fly over to-morrow night. If we can get Mademoiselle Pasquet out she can hide here quite safely for a few hours, but there will be a very close search when her escape is discovered."

"I'll get the message to Manton at once," said Jules.

And so it happened that d.i.c.k and Le Couteur, who had been waiting for hours in a state of tense anxiety, received a few minutes later the call.

"M M M begins To-morrow night stop Come early as possible stop Three lights in triangle safe stop Four keep off M M M ends."

"At last," said d.i.c.k grimly, with a look on his face that boded ill for some one. He looked drawn and haggard, and even Le Couteur could hardly repress a shudder at the savage determination that blazed in his eyes.

For Yvette the next day was one of misery. Time after time she was dragged from her cell and taken before the Governor of the prison, and Kranzler, to be pitilessly cross-questioned and even threatened with violence. But even though she knew well that the two brutes were quite capable of carrying out their threats nothing could break the spirit of the French girl. To all their questions and menaces she turned a deaf ear and nothing they could say would induce her to affirm or deny anything. Utterly worn out she was at length roughly bundled back into her cell, where she dropped exhausted on the miserable apology for a bed. At least she was alone.

It was about five o'clock and she had fallen into an uneasy doze, when she was awakened by a slight noise at the door. She saw the observation grille slide back and, pushed through the grating, a tiny parcel fell with a subdued clink on the floor. Then the grating was closed.

Hastily she sprang to her feet and seized the parcel, a new hope surging in her breast. It could only mean help!

Inside the parcel was a letter, unsigned of course, but in Jules'

handwriting, and a small key.

Nine o'clock came, and with all the wearisome ceremony dear to the German heart, the guard, accompanied by a wardress, made its final inspection for the night. A few minutes after the big prison was as silent as the grave.

Half an hour later Yvette cautiously fitted the key into the lock. It had been well oiled, and the door swung open without a sound. Creeping down the flight of steps Yvette found that the key also opened the door at the bottom, and in a moment she was in the yard.

Rain was falling heavily. There was not a ray of light in the yard excepting a faint gleam which showed the position of the warders'

lodges.

Before leaving her cell Yvette had pulled her stockings over her boots, and moving without a sound she groped her way along the wall. A few feet from the door she found the big stackpipe which brought the rain water from the roof. Stooping she lifted the iron grid of the drain and thrust in her hand. Her fingers closed on the b.u.t.t end of the gas pistol.

Silently, following along the wall in preference to crossing the courtyard, she stole towards the lodge. Complete surprise was essential.

With the pistol ready in her hand, she softly opened the door of the lodge on the right of the gateway. Luck was with her again. The two men, in defiance of rules, were in the same lodge talking quietly.

The noise of the door opening brought them to their feet with a jump.

But they were too late. Only ten feet away from them Yvette pulled the trigger twice in rapid succession. There was no more noise than a slight hiss as the gas escaped and the two men dropped insensible.

s.n.a.t.c.hing up a bunch of keys from the table, Yvette herself half-stifled, quickly got outside and closed the door. A moment later she had opened the wicket-gate and slipped through. She almost fell into the arms of Jules and Gaston, and at top speed the three raced through the rain for Gaston's farm.

Luckily, the pouring rain swiftly obliterated their footprints, but they had hardly got into hiding, wet through but triumphant, when pandemonium broke out in the prison, and the frantic ringing of the big bell announced the escape of a prisoner. The two warders, of course, had speedily recovered, and hastened to tell their story, and a quick search had revealed that Yvette's cell was empty. A few minutes later search parties were hurrying in every direction in pursuit of the fugitive.

Gaston's farm, lying close to the prison, was naturally one of the first places to be visited. Gaston, smoking peacefully by the fireside, soon heard, as he expected, the savage clamour of dogs in the farmyard mingled with agonised cries for help.

He hurried out. Two warders, one of them badly bitten, were backed against the fence, hardly keeping at bay with their sticks a couple of powerful dogs.

Gaston called off the dogs and, full of apparent solicitude, expressed his regret. He listened to the guards' explanation.

"She cannot have been here," he declared, "the dogs would have bitten her to pieces. But, of course, we will look round if you like."

The guards, however, were more than satisfied. Gaston's argument was backed by their own experience, and they were quite ready to be convinced if they could only get away from the ferocious dogs who continually prowled about snarling as though even the presence of their master was hardly sufficient to protect his visitors. They little dreamed that the savage brutes would indeed have torn Yvette to pieces had not Gaston thoughtfully taken the precaution to lock them up before he and Jules started to rescue her!

Away at Verdun d.i.c.k stood beside the Mohawk waiting impatiently in the dark. Time and again he had tested every nut and screw in the machine; time and again he had run the powerful engine to make sure that it was in working order.

At last the longed for moment for action came. Anything was better than long drawn-out suspense.

He wrung Le Couteur's hand as he stepped into the machine.

"I'll be back with her by dawn," he said, "or else--" there was no need to finish the sentence.

He had not gone five minutes before Le Couteur received a message from Jules announcing that Yvette had escaped. If only d.i.c.k had known!

It was raining hard when the Mohawk rose into the air, but d.i.c.k was beyond caring for the weather, and anxious only for Yvette, he sent the helicopter tearing through the darkness eastward to Berlin. He drove almost automatically, his thoughts intent on the girl ahead of him.

As he approached Berlin, the weather cleared and the rain stopped. All around him were the navigation lights of the German mail and pa.s.senger planes, hurrying to every quarter of the Empire, and, even in his anxiety, d.i.c.k was conscious of an uneasy feeling of irritation at the thought that England was being left so far behind in the race for the mastery of the air.

Then he caught sight of the great beams of light that marked the position of the huge Berlin aerodrome, and a few minutes' flying brought him above Spandau. He circled twice, looking for Gaston's signals, and at last he dropped lower, caught the gleam of the three lanterns which Gaston had placed to guide him, and brought the machine swiftly down beside the big barn. Then he leaped from his seat.

He nearly gave a shout of joy that would have aroused every German within a mile! For there, in the light of the lanterns, stood Yvette herself.

There was no time for explanation.

"Now's your chance," gasped Jules, wild with excitement, "the German plane has just gone up!"

d.i.c.k's face hardened instantly.

"Get in, Yvette," he said curtly.