He stood quite still for fully five minutes to make sure that they had really gone, and then he stole with catlike tread over the noiseless carpet, and, opening the door, listened again.

The billiard-room was at the opposite end of the vestibule, and, closing the door gently behind him, he switched on the electric light, which revealed Mademoiselle Van Drissel evidently waiting for him.

"What have you learned, Anton?" she whispered in German.

"I have learned everything, my little wife," he replied. "We leave this house to-morrow, as soon as those two fools have gone to catch their boat-train."

"Zo!" she exclaimed, clasping her hands. "I, for one, shall be delighted. I shall have but one regret."

"And what is that, Ottilie?" inquired her husband.

"That I shall not be able to twist the neck of that detestable little pig-dog, Billy, before I go. Ach, Anton, you do not know how I hate the little beast!"

"I do not love him myself," said the spy, seating himself beside her. "Listen, this is a good opportunity for us to talk without interruption, and there is much to be arranged. You will stay in London; I shall cross over to-morrow night from the usual place, for my information must be in the Kaiser's hands without delay. It is now June 20, and the great attack is to take place on the first day of July."

As he spoke he drew out a pocket-book, and the girl leaning over his shoulder read the words he wrote down rapidly while all he had overheard was still fresh in his memory.

"Is it possible?" murmured his female confederate. "Our time has not been wasted after all, then. Our people knew what they were doing when they sent us to this house."

"Our people always know what they are doing," said the sham Belgian, with a cunning leer. "What would you have? A family, the father of which is a brigadier-general at the front; the eldest son also a captain at the front; and the young boy on the point of joining the Army. They were just the very people likely to talk, to say nothing of that greatest fool of all, Uncle Staff Captain, who told me a great deal when he dined here on Wednesday. Ottilie, these English are lunatics, and it is not for nothing that we have opened their letters for the last six months without their discovering it. Still, I must confess I had never expected a piece of luck so complete and so timely as this," and he tapped the notebook in which he had recorded everything.

He stooped towards her and kissed with as much affection as lies in the German nature to bestow upon anyone outside itself, and when he spoke again his whisper was very earnest.

"You had a headache to-night—good. You can make the excuse in the morning to visit the pharmacy in Shaftesbury Avenue. I need not tell you where you will really go. But tell them that word must be sent to Fritz Hoffer to take me off at the old spot at seven o'clock to-morrow night."

"Are you certain of a train that will get you there in time?"

"I shall not bother about trains," he replied. "The Kilburn Rifles are doing coast duty there, and I will borrow Dennis Dashwood's motor-bike ten minutes after their car has left for Charing Cross. I shall be in the vicinity of Folkestone before their train arrives, and may possibly pass them in the Channel."

"Sure everything's in?" said Captain Bob with a keen glance round the hall, which looked so pathetically empty now that the little pile of brown cases had been carried to the car. "Well, time's up. Au revoir, mon lieutenant. I must air my bad French, you know," and he shook hands warmly with the "Belgian officer," who stood bareheaded on the step to see them off. "Hope to meet you over there one of these days. Buck up and get all right, you know."

"We shall meet, never fear; perhaps sooner than you think," said Van Drissel with a quiet smile. "Good-bye and good luck to you both."

Then the skunk saluted, and the car drove off, Mademoiselle Ottilie waving her handkerchief. Now they were gone, and as the three little girls filed back into the hall wiping their eyes, the Van Drissels exchanged a look."You have nothing that matters if you leave it behind?" said the man.

"Nothing at all—a refugee is not supposed to have belongings," replied his wife.

"Very well, do not go yet until you have heard me start the engine. Then when I have gone, walk quietly out of the house just as you are. They might trace a taxi."

The motor-car came to a stand outside Charing Cross Station, and Mrs. Dashwood's heart seemed to come to a stand with it. In less than half an hour she knew she would have parted with her boys, perhaps for the last time, but she kept a brave face as Bob helped her out, and they found themselves on the fringe of the busy throng that every day marks the departure of the boat-train.

There were not quite so many people as usual, for nearly all leave had been stopped.

A porter, well over military age, followed them through the barrier on to No. 2 platform, where the long train was waiting. Three men of the Lincolns, loaded with packs and rifles and bulging haversacks, were looking for three seats in the same compartment.

A family of eight, of assorted sizes, were gathered round a short private of the A.S.C., all talking at once. Farther along, a very pale officer of the Northamptons, going out for the first time, stood with three ladies, keeping his end up very well. Three lieutenants going back from short leave, and lucky to get it, stood chattering, with red V's on the back of their tunics, and as he passed them Dennis saw that they belonged to the Northumberland Fusiliers.

Bob had secured places in the Pullman, and they walked along the train until they reached it, and read the name "Clementina, seats 1-19," and when their clobber had been put inside they stood on the curving platform, watching the scene.

A chaplain with three stars on his black shoulder-straps and a pipe in his mouth was talking to a tall curate, and two French officers in the new blue-grey uniform, with black belts and gaiters, gave a touch of unusual colour as they passed backwards and forwards through the groups. One of them had a long beard; the other, a merry little man talking very good English to three friends, wore the red ribbon of the Military Cross on his breast.

Quite a number of British staff officers came along, one with a very purple face, and the three Lincolns, who had been turned out of a second-class carriage, made their way back again in search of a third.

A collector came along and examined the tickets, and everyone drew a little closer to his carriage door.

"Only five minutes now," said Bob, glancing at the clock.

The staff officer with the purple face sat in his corner in the dining-car, but almost everybody else was still out on the platform.

Then the railway officials moved quietly among the little groups, saying: "Time is up, gentlemen. Please take your seats," and the little groups separated, the officers climbing into the carriages.

From the rear of the platform a low whistle sounded, and another official pressed a button close to the clock at the other end and blew a little note himself. That was all, and almost imperceptibly the boat-train glided away, with here and there a wave of a khaki arm, and from the third-class compartments at the end a heedless cheer from some youngsters who were going back again and did not seem to mind.

"What is this, Smithson?" said Mrs. Dashwood, as the parlourmaid handed her an envelope when she reached home.

"Mademoiselle asked me to give it to you as soon as you arrived, ma'am," said the maid, and she opened the letter.

"Good heavens! What vile ingratitude!" exclaimed Mrs. Dashwood. "I have harboured spies!"

A drizzling rain blurred the Channel, and it was high tide.

The lap of the wavelets on the pebbles sounded in the ears of a sentry who swung suddenly round and challenged, rather surprised to see by the scarlet band that the man who had approached to within two paces of him unheard was a staff officer."That's all right, my boy, you needn't look so flurried," said the "brass hat." "Do you know if the boat has gone over yet?"

"I ain't seen her, sir, but, then, you can't see much in this drizzle. But I'll tell you what happened last night, sir; them there lights showed again up yonder."

"That is precisely what I have been sent down to investigate," said his interrogator.

"We are all certain there's something going on," said the sentry, "though they ain't been seen for ten days now."

They stood side by side looking inland, and the staff officer, with his hands behind the back of his drab mackintosh, pressed the button of a tiny electric torch rapidly three times.

The sentry was only a boy, and he talked volubly, not heeding the melancholy call of a sea-bird from the water.

"Ah, well, I think we shall have them to-night," said the staff officer. "I see you have still got the old Mark II.?"

"Yes, sir," smiled the unsuspecting lad. "They took the others away from us when we came down on this job."

"Let me look at it," said the staff captain, holding out his hand, and the moment his fingers closed round the rifle the boy dropped senseless on to the stones, felled by a smashing blow from the heavy butt.

"You'll do!" said his assailant, and, laying the rifle down and gathering up the skirts of his mackintosh, he walked deliberately into the sea!

A collapsible boat, rowed by two men in German naval uniforms, was rising and falling on the top of the tide, and in another moment the men were pulling out into the rain blur with their mysterious passenger.

No one spoke, until the nose of the boat met the dark grey hull of the submarine waiting less than a quarter of a mile out, and as the beam of a searchlight suddenly flashed through the mist, the top of the periscope sank noiselessly beneath the waves, and Captain Von Dussel, alias Van Drissel, sank with it.

"Good luck again, Kamerad?" inquired the commander as they stood in the conning-tower.

"The best of good luck this time, Heffer," laughed the spy. "How soon can you put me ashore on the other side?"

"As soon as I have accomplished a little scheme of my own," replied the commander of the U50, with a strange glitter in his eyes. "The boat is coming out of Folkestone now."

"That is not my affair," said Von Dussel.

"No, it is mine," replied the commander haughtily. "In less than an hour I shall send her to the bottom."

"You will do no such thing," said the spy in a low piercing voice, producing a Browning pistol and clapping it to his head. "In an hour I must be in France. The news I carry is worth the loss of forty Channel steamers. Hesitate another moment, and I will shoot you like a dog!"