It was towards the close of an unusually long day's work and Major Thomson sighed with relief as he realised that at last his anteroom was empty. He lit a cigarette and stretched himself in his chair. He had been interviewed by all manner of people, had listened to dozens of suspicious stories. His work had been intricate and at times full of detail. On the whole, a good day's work, he decided, and he had been warmly thanked over the wires by a Brigadier-General at Harwich for his arrest and exposure of a man who had in his possession a very wonderful plan of the Felixstowe land defences. He lit a cigarette and glanced at his watch. Just then the door was hurriedly opened. Ambrose came in without even the usual ceremony of knocking. He held a worn piece of paper in his hand. There was a triumphant ring in his tone as he looked up from it towards his chief.

"I've done it, sir!" he exclaimed. "Stumbled across it quite by accident. I've got the whole code. It's based upon the leading articles in the Times of certain dates. Here's this last message--'Leave London June 4th. Have flares midnight Buckingham Palace, St. Paul's steps, gardens in front of Savoy. Your last report received.'"

"'Leave London June 4th,'" Thomson repeated, glancing at his calendar,--"to-day! 'Have flares,'--Zeppelins, Ambrose!"

The clerk nodded.

"I thought of them at once, sir," he agreed. "That's a very plain and distinct warning in a remarkably complicated code, and it's addressed--to Sir Alfred Anselman."

A smouldering light flashed in Thomson's eyes.

"Ambrose," he declared, "you're a brick. I sha'n't forget this. Just find out at once if the Chief's in his room, please."

There followed half an hour of breathless happenings. From the Chief's room Thomson hurried over to the Admiralty. Here he was taken by one of the men whom he had called to see, on to the flat roof, and they stood there, facing eastwards. Twilight was falling and there was scarcely a breath of air.

"It's a perfect night," the official remarked. "If they start at the right time, they'll get here before any one can see them. All the same, we're warning the whole coast, and our gun-stations will be served all night."

"Shall we have a chance, do you think, of hitting any of them?" Thomson asked.

The sailor winked.

"There are a couple of gun-stations I know of not far from here," he said. "I tell you they've got armament there which will make our friends tear their hair' shells that burst in the air, mind, too, which you needn't mind letting 'em have as quick as we can fire 'em off. I shall try and get on to one of those stations myself at midnight."

"What time do you think they'd attack if they do get over?"

The other took out his watch and considered the subject.

"Of course," he reflected, "they'll want to make the most of the darkness, but I think what they'll aim at chiefly is to get here unobserved. Therefore, I think they won't start until it's dark, probably from three or four different bases. That means they'll be here a little before dawn. I shall just motor my people up to Harrow and get back again by midnight."

Thomson left the Admiralty, a little later, and took a taxi to Berkeley Square. The servant hesitated a little at his inquiry.

"Miss Geraldine is in, sir, I believe," he said. "She is in the morning-room at the moment."

"I shall not keep her," Thomson promised. "I know that it is nearly dinner-time."

The man ushered him across the hall and threw open the door of the little room at the back of the stairs.

"Major Thomson, madam," he announced.

Geraldine rose slowly from the couch on which she had been seated. Standing only a few feet away from her was Granet. The three looked at one another for a moment and no word was spoken. It was Geraldine who first recovered herself.

"Hugh!" she exclaimed warmly. "Why, you are another unexpected visitor!"

"I should not have come at such a time," Thomson explained, "but I wanted just to have a word with you, Geraldine. If you are engaged, your mother would do."

"I am not in the least engaged," Geraldine assured him, "and I have been expecting to hear from you all day. I got back from Boulogne last night."

"None the worse, I am glad to see," Thomson remarked.

She shivered a little. Then she looked him full in the face and her eyes were full of unspoken things.

"Thanks to you," she murmured. "However," she added, with a little laugh, "I don't want to frighten you away, and I know what would happen if I began to talk about our adventure. I am sorry, Captain Granet," she went on, turning towards where he was standing, "but I cannot possibly accept your aunt's invitation. It was very good of her to ask me and very kind of you to want me to go so much, but to-night I could not leave my mother. She has been having rather a fit of nerves about Ralph the last few days, and she hates being left alone."

"Captain Granet is trying to persuade you to leave London this evening?" Thomson asked quietly.

"He wants me very much to go down to Lady Anselman's at Reigate to-night," Geraldine explained. "I really accepted Lady Anselman's invitation some days ago, but that was before mother was so unwell. I have written your aunt, Captain Granet," she continued, turning to him. "Do please explain to her how disappointed I am, and it was very nice of you to come and ask me to change my mind."

There was brief but rather curious silence. Granet had turned away form Geraldine as though to address Thomson. He was meeting now the silent, half contemptuous challenge of the latter's eyes.

"Captain Granet is showing great consideration for your comfort and safety," Thomson remarked.

Granet for a moment forgot himself. His eyes flashed. He was half angry, half terrified.

"What do you mean?" he demanded.

Thomson made no immediate answer. He seemed to be pondering over his words, his expression was inscrutable. Geraldine looked from one to the other.

"There is something between you two which I don't understand," she declared.

"There is a very great deal about Captain Granet which I am only just beginning to understand," Thomson said calmly. "You should find his solicitude about your movements this evening a great compliment, Geraldine. It arises entirely from his desire to spare you the shock of what may turn out yet to be a very lamentable catastrophe."

"You two men are quite incomprehensible," Geraldine sighed. "If only either of you would speak plainly!"

Thomson bowed.

"Perhaps I may be able to indulge you presently," he observed. "Since you have failed to persuade Miss Conyers to leave London, Captain Granet," he went on, turning towards the latter, "may I ask what your own movements are likely to be?"

"You may not," was the passionate reply. "They are no concern of yours."

"They are unfortunately," Thomson retorted, "my very intimate concern. This, you will remember, is your ninth day of grace. It is not my desire that you should suffer unduly for your humane visit here, but I might remind you that under the circumstances it is a little compromising. No, don't interrupt me! We understand one another, I am quite sure."

Granet had taken a step backwards. His face for a moment was blanched, his lips opened but closed again without speech. Thomson was watching him closely.

"Precisely," he went on. "You have guessed the truth, I can see. We have been able, within the last few hours, to decode that very interesting message which reached your uncle some little time ago."

Geraldine's bewilderment increased. Granet's almost stupefied silence seemed to amaze her.

"Hugh, what does it all mean?" she cried. "Is Captain Granet in trouble because he has come here to warn me of something? He has not said a word except to beg me to go down into the country tonight."

"And he as begged you to do that," Thomson said, "because he is one of those privileged few who have been warned that to-night or to-morrow morning is the time selected for the Zeppelin raid on London of which we have heard so much. Oh! He knows all about it, and his uncle, and a great many of the guests they have gathered together. They'll all be safe enough at Reigate! Come, Captain Granet, what have you to say about it?"

Granet drew himself up. He looked every inch a soldier, and, curiously enough, he seemed in his bearing and attitude to be respecting the higher rank by virtue of which Thomson had spoken.

"To-morrow, as you have reminded me, is my tenth day, sir," he said. "I shall report myself at your office at nine o'clock. Good-bye, Miss Conyers! I hope that even though I have failed, Major Thomson may persuade you to change your mind."

He left the room. Geraldine was so amazed that she made no movement towards ringing the bell. She turned instead towards Thomson.

"What does it mean? You must tell me!" she insisted. "I am not a child."

"It means that what I have told you all along is the truth," Thomson replied earnestly. "You thought, Geraldine, that I was narrow and suspicious. I had powers and an office and responsibilities, too, which you knew nothing of. That young man who has just left the room is in the pay of Germany. So is his uncle."

"What, Sir Alfred Anselman?" she exclaimed. "Are you mad, Hugh?"

"Not in the least," he assured her. "These are bald facts."

"But Sir Alfred Anselman! He has done such wonderful things for the country. They all say that he ought to have been in the Cabinet. Hugh, you can't be serious!"

"I am so far serious," Thomson declared grimly, "that an hour ago we succeeded in decoding a message from Holland to Sir Alfred Anselman, advising him to leave London to-day. We are guessing what that means. We may be right and we may be wrong. We shall see. I come to beg you to leave the city for twenty-four hours. I find Granet on the same errand."

"But they may have warned him--some personal friend may have done it," she insisted. "He is a man with world-wide friends and world-wide connections."

"They why didn't he bring the warning straight to the Admiralty?" Thomson argued. "If he were a patriotic Englishman, do you think that any other course was open to him? It won't do, Geraldine. I know more about Captain Granet than I am going to tell you at this moment. Shall we leave that subject? Can't we do something to persuade your mother to take you a little way from town? You can collect some of your friends, if you like. You ought to take Olive, for instance. We don't want a panic, but there is no reason why you shouldn't tell any of your friends quietly."

The door was suddenly opened. The Admiral put his head in.

"Sorry!" he apologised. "I thought I heard that young Granet was here."

"He has been and gone, father," Geraldine told him. "You'd better see what you can do with father," she added, turning to Thomson.

"What's wrong, eh? What's wrong? What's wrong?" the Admiral demanded.

"The fact is, Sir Seymour," Thomson explained, "we've had notice--not exactly notice, but we've decoded a secret dispatch which gives us reason to believe that a Zeppelin raid will be attempted on London during the next twenty-four hours. I came round to try and induce Geraldine to have you all move away until the thing's over."

"I'll be damned if I do!" the Admiral grunted. "What, sneak off and leave five or six million others who haven't had the tip, to see all the fun? Not I! If what you say is true, Thomson,--and I am going straight back to the Admiralty,--I shall find my way on to one of the air stations myself, and the women can stay at home and get ready to be useful."

Geraldine passed her hand through her father's arm.

"That's the sort of people we are," she laughed, turning to Thomson. "All the same, Hugh, it was very nice of you to come," she added. "I couldn't see us scuttling away into the country, you know. I shall go round and persuade Olive to stay with me. I am expecting to return to Boulogne almost at once, to the hospital there, to bring some more wounded back. I may get a little practice here."

Thomson picked up his hat.

"Well," he said quietly, "I cannot complain of your decision. After all, it is exactly what I expected."

He made is adieux and departed. The Admiral sniffed as he glanced after him.

"Very good chap, Thomson," he remarked, "but he doesn't quite understand. I bet you that fine young fellow Granet would never have suggested our running away like frightened sheep! Come along, my dear, we'll go and dine."