Erich von Stalhein was in a very different category. In appearance he was tall, slim, and good-looking in a rather foppish way, but he had been a soldier for many years, and there was a grim relentlessness about his manner that quickly told Biggles that he was a man to be feared. He had been wounded early in the war, and walked with a permanent limp with the aid of two sticks, and this physical defect added something to his sinister bearing. Unlike most of his countrymen, he was dark, with cold brooding eyes that were hard to meet and held a steel-like quality that the monocle he habitually wore could not dispel. Such was Hauptmann Erich von Stalhein, the officer to whom Biggles had reported in Zabala and who had conducted him into Count von Faubourg's office for interview.

Biggles sensed a latent hostility from the first moment that they met, and felt it throughout the interview. It was almost as if the man suspected him of being an imposter but did not dare to question the actions of those who had been responsible for his employment. Whether or not von Stalhein was aware that he, as Lieutenant Brunow, had previously served in the British R.F.C. he did not know, nor did he think it wise to inquire. Of one thing he was quite certain, however, and that was that the German would watch him like a cat watching a mouse, and pounce at the first slip he made.

Another thing he noticed was that all the Germans engaged in Intelligence work wore a signet ring like the one that had been given to him by Broglace; it appeared to be a kind of distinguishing mark or identification symbol. The Count wore one, as did von Stalhein and Leffens; he had also seen one or two other officers wearing them. His own, when opened, displayed a tiny dagger suspended over a double-headed eagle, with a small number 117 engraved below. Just how big a part it played in the German espionage system he had yet to learn.

If he had been sent to Zabala for any special reason he had not yet been informed of it.

The Count, his Chief had merely said that he would be employed in the most useful capacity at the earliest opportunity, but in the meantime he was to make himself acquainted with the positions of the battle fronts. Nevertheless he suspected that his chief duty would be to land behind the British lines, for the purpose of either gathering information or verifying information that had already been acquired through other channels. In this he was not mistaken.

Of El Shereef he had seen no sign-not that he expected to. The name was almost a legend, hinted at rather than spoken in actual words. Still, there was no doubt that the man existed: General Pendersby had a.s.sured him of that. He could only keep his ears and eyes open and wait for some clue that might lead to the identification of the German super-spy.

At this period of the war the German Secret Service in Palestine was the most efficient in the world, and of its deadly thoroughness he was soon to have a graphic example. Quite unaware of this, he reached Zabala without incident, and after making a neat landing, taxied into the hangar that had been reserved for the British machines. He did not report to the office at once, but went to his quarters, where he changed into his German uniform. Naturally the British uniform was not popular, and for this reason he invariably wore overalls when he was compelled to wear it. Having changed, he made his way slowly to the Officers' Mess* with a view to finding a quiet corner in order to study a German grammar he had bought, for his weak knowledge of the language was one of the most serious difficulties with which he was faced, and for this reason he had worked hard at it since his arrival in German territory.

He had not been seated many minutes when an orderly entered and handed him a note from the Count requesting his presence at the Headquarters office immediately. With no suspicion of anything unusual in his mind, he put the book in his pocket, picked up his cap, and walked down the tarmac to the old Turkish fort that served both as his Chiefs headquarters and as sleeping quarters for the senior officers, while the courtyard and stables had been converted, by means of barbed wire, into a detention barracks for prisoners of war.

He knocked at the door and entered. The Count was leaning back in his chair with the collar of his tunic unfastened, in conversation with von Stalhein, who half sat and half leaned against the side of the desk. A fine coil of blue smoke arose lazily from the cigarette he was smoking in a long amber holder, and this, with the rimless monocle in his eye, only served to accentuate his effeminate appearance; but as he took in these * The place where officers eat their meals and relax together.

details with a swift glance, Biggles thought he detected a sardonic gleam in the piercing eyes and experienced a twinge of uneasiness. He felt rather than saw the mocking expression that flitted across von Stalhein's face as he stood to attention and waited for the Count to speak.

'So! Here you are, Brunow,' observed von Faubourg easily. 'You went out flying this morning-yes?' He asked the question almost casually, but there was a grim directness of purpose about the way he crouched forward over his desk.

Biggles sensed danger in the atmosphere, but not by a quiver of an eyelid did he betray it. 'I did, sir, acting under your instructions,' he admitted calmly.

'Why did you land behind the British lines?' The easiness had gone from the Count's manner; he hurled the question like a spear.

Biggles turned stone-cold; he could feel the two pairs of eyes boring into him, and knew that if he hesitated he was lost. 'Because I thought it would be a good thing to ascertain immediately if such landings could be made with impunity,' he replied coolly. 'The occasion to land in enemy country might arise at any time, and it seemed to me that a preliminary survey of the ground for possible danger was a sensible precaution.'

The Count nodded slowly. 'And is that why you visited the Headquarters tent of the British Intelligence Service?'

Biggles felt the muscles of his face grow stiff, but he played his next card with a steadiness that inwardly amazed him. His lips parted in a smile as he answered carelessly and without hesitation, 'No, sir. I had no choice in that matter. I was sent for-it was all very amusing.'

'How?'

'The idea of being invited into the very place which I imagined would be most difficult to enter. I am afraid I have not been engaged in this work long enough to lose my sense of humour.'

'So it would seem. Why were you sent for?'

'Because I had said in the Officers' Mess that I was a delivery pilot*, and he-that is, the officer who sent for me-was merely interested to know if I was going to Heliopolis as he had a personal message for some one stationed there.'

'What did you say?'

I told him I was sorry, but I was not going near Heliopolis.'

anything else?'

'Nothing, sir. The matter ended there and I came back.'

'Who was the other officer with Major Raymond?'

The words reacted on Biggles's tense nerves like an electric shock; there seemed to be no limit to German knowledge of British movements. 'No wonder we are getting the worst of it,' was the thought that flashed through his mind, as he answered with all the non-chalance he could muster, 'I've no idea, sir. I saw another officer there, a young fellow, but I did not pay any particular attention to him. If I thought anything at all I imagined him to be an a.s.sistant of some sort.'

'You knew the other was Major Raymond, who has just arrived here from France?'

I know now, sir. I was told to report to Major Raymond: that's how I knew his name. I knew nothing * The pilot who delivers aeroplanes to service squadrons from the manufacturers or repair depots.

about his just having arrived until you told me a moment ago.'

'Have you ever seen him before?'

'Not to my knowledge.'

'He didn't recognize you?'

Oh, no, sir-at least, I have no reason to suppose he did. He was quite friendly.'

The answer apparently satisfied the Count, for he looked up at von Stalhein with a look which said as plainly as words, 'There you are: I told you so. Quite a natural sequence of events.' But von Stalhein was still watching Biggles with a puzzled smile, and continued to do so until the Count told him that he might return to his quarters, although he must remain at hand in case he was needed.

Biggles drew a deep breath as he stepped out into the blazing sunshine. His knees seemed to sag suddenly, and his hands turned ice-cold although they did not tremble. 'My word! I've got to watch my step and no mistake; these people have eyes everywhere,' he reflected bitterly, and not without alarm, as he walked slowly towards his quarters.

Chapter 4.

A Meeting and a Duel He had just finished dressing the following morning when his presence was again demanded by Count von Faubourg. His mind ran swiftly over his actions since the last interview, and although he could think of nothing he had done that could be regarded as a suspicious action, it was with a feeling of trepidation that he approached the fort. 'It's this beastly ever-present possibility of the unknown, the unexpected, turning up, that makes this business so confoundedly trying,' he thought, as he knocked on the door.

As he entered the office he instinctively looked round for von Stalhein, but to his infinite relief he was not there. Moreover, the Count seemed to be quite affable.

'Good morning, Brunow,' he called cheerfully. 'I have a real job for you at last.'

'Thank you, sir,' replied Biggles, with an enthusiasm he certainly did not feel. 'I shall be glad to get down to something definite.'

I thought perhaps you would,' answered the Count. Now this is the position. We have received word that a large body of British troops, chiefly Australian cavalry, has recently left Egypt. There is a remote chance that they may have gone to Salonika, but we do not think so. It is far more likely that they have been disembarked and concealed somewhere behind this particular front in readiness for the big push which we know is in course of preparation. You may find it hard to believe that twenty thousand men can be moved, and hidden, without our being aware of their destination, but such unfortunately is the case. The British have learnt a bitter lesson, and they are acting with circ.u.mspection. I want you to try to find those troops. If they are in Palestine, then it is most likely that they are somewhere in the hills- here.'

He indicated an area on his large-scale wall-map. 'Search there first, anyway,' he continued. 'The fact that our reconnaissance machines have been driven off every time they have attempted to approach that zone suggests that our deductions are correct; if you will take one of the British machines you will not be molested. If you cannot find the camp from the air it may be necessary for you to land and make discreet inquiries.'

'Very good, sir.' Biggles saluted, returned to his quarters, put on his British uniform and his overalls, and then made his way to the hangar where the British machines were housed. He ordered the mechanics to get out the Sopwith Pup,* and then glanced along the tarmac as an aero-engine came to life farther down. A silver and blue .Pfalz Scout**

was taxi-ing out into position to take off, and he watched it with interest as its tail lifted and it climbed swiftly into the shimmering haze that hung over the sandy aerodrome.

'That's Leffen's machine; I wonder what job he's on,' he mused, as he climbed into his c.o.c.kpit, started the engine, and waited for it to warm up. But his interest in the other machine waned quickly as he remembered the difficult work that lay before him, for the task was one of the sort he had been dreading.

* Single seater biplane fighter with a single machine gun synchronised to fire through the propeller. Superseded by the Sopwith Camel. ** Very successful German single-seater biplane fighter, fitted with two or three machine guns synchronised to fire through the propeller. See cover ill.u.s.tration.

To report the position of the Australian troops to the Germans, even if he discovered it, was obviously out of the question; yet to admit failure, or, worse still, name an incorrect position that the enemy would speedily prove to be false, was equally impossible.

I'd better try to get word to Raymond and ask him how I am to act in cases of this sort; maybe he'll be able to suggest something,' he thought, as he pushed open the throttle and sped away in the direction of the British lines. For some time, while he was in sight of the aerodrome, he held steadily on a course that would take him over the area indicated by von Faubourg, but as the aerodrome slipped away over the horizon behind him he turned north in the direction of Abba Sud.

A few desultory bursts of German archie blossomed out in front of him, but he fired a green Very light, thefriendly' signal that had been arranged for him by headquarters and the German anti-aircraft batteries, and they died away to trouble him no more.

He kept a watchful eye open for prowling German scouts, who would, of course, shoot him down if they failed to notice the white bar that had been painted across his top plane for identification purposes, but he saw nothing, although it was impossible to study the sky in the direction of the blazing tropical sun. 'I hope to goodness Algy is about,' he thought anxiously, twenty minutes later, as he peered through his centre section in the direction of the oasis.

He searched the sky in all directions, but not a sign of a British machine could he see, and he was about to turn away when something on the ground caught his eye. It was a Very light that curved upwards in a wide arc, and staring downward he made out an aeroplane bearing the familiar red, white, and blue marking standing in the shade of the palms that formed the oasis.

'By jingo, he's down there,' he muttered in a tone of relief, as he throttled back and began to drop down towards the stationary aeroplane. A doubt crossed his mind about the suitability of the sand as a landing surface, but realizing that the R.E.8*-for as such he recognized the waiting machine-must have made a safe landing, he glided in and touched his wheels as near to the trees as possible.

Somewhat to his surprise, he saw two figures detach themselves from the shadows and walk quickly towards him, but when he identified them as Algy and Major Raymond he smiled with satisfaction and relief. 'This is better luck than I could have hoped for,' he called, as he switched off, and hurried to meet them.

I had an idea you'd be over to-day, so I got Lacey to bring me along,' returned the Major as he shook hands. 'Well, how are things going?'

'They're not going at all, as far as I can see,' answered Biggles doubtfully. I'm supposed to be looking for this fellow El Shereef, but I haven't started yet, for the simple reason that I haven't the remotest idea of where to begin; I might as well start looking for a pebble in the desert. I'm scared stiff of making a b.o.o.b, and that's a fact. Do you know that by the time I got back yesterday the Huns knew I had been to see you?'

Impossible,' cried the Major aghast.

'That's what I should have said if it had been any one else, but you wouldn't have thought so if it had been you standing on the mat in front of the Count, and that swine von Stalhein,' declared Biggles, with a * British two-seater biplane designed for reconnaissance and artillery observation.

marked lack of respect. don't mind telling you that I could almost hear the tramp of the firing party when the Old Man pushed the accusation at me point blank. I went all groggy, but I lied like a trooper and got away with it. That's what I hate about this spy game: it's all lies; in fact, as far as I can see, n.o.body fells the truth.'

I'm sorry, but it's part of the game, Bigglesworth,' put in the Major quickly. 'What excuse have you made for getting away this morning?'

'No excuse was necessary; I've been sent out on a job, and that's why I'm so glad to see you.' In a few words he explained his quest.

The Major looked grave. 'It's very difficult, and how the Huns knew about these reinforcements is more than I can imagine,' he observed, with a worried frown. 'No, by Jove! There is a way,' he added quickly.

I'm glad to hear that,' murmured Biggles thankfully.

The Australian troops are hidden in the palm-groves around Sidi Arish, but they are leaving there to-night to take their places in the support trenches. You can report their position at Sidi Arish when you get back, and it will be quite safe; von Faubourg will get a photographic machine through by hook or by crook, and he will see that you are correct. The chances are that he will launch a bomb raid to-night, after midnight, by which time the Australians will have gone. In that way we can kill two birds with one stone. You'll put your reputation up with von Faubourg, and consolidate your position, and the Huns will waste a few tons of bombs.'

'Fine! We couldn't have planned a better situation,' declared Biggles delightedly. 'And look here, Algy, while I think of it. I have been wondering how you could get a message through to me in case of emergency. There's only one way that I can think of and it's this, although it mustn't be done too often. Behind our aerodrome at Zabala there's a large olive-grove. You could fly over low at night and drop a non-committal message, cutting your engine twice in quick succession as a signal to let me know that you've done it.'

It sounds desperate,' observed Algy doubtfully.

It is, but it would only be done to meet desperate circ.u.mstances.'

'Quite, and I think it's a good idea,' broke in the Major. 'I've only one more thing to say. I'

m afraid you won't like it, but an idea has been put up to me by H.Q., although they have no idea, of course, of the means I might employ to carry it out. As you are probably aware, the German troops along a wide sector of this front get their water by a pipe-line that is fed from the reservoir just north of your aerodrome.'

I've noticed the reservoir from the air, but I didn't know it watered the troops. What about it, sir?'

'Can you imagine what a tremendous help it would be to us in making preparations for the next big attack if that water-supply failed?'

I hope you are not going to ask me to empty the water out of the reservoir,' smiled Biggles.

'No, I was going to ask you to blow it up.'

The smile disappeared from Biggles' face like magic, and he staggered. 'Great goodness!'

he gasped; 'you're not serious, sir?'

'Would I be likely to joke at such a juncture?' 'But you can't make troops die of thirst.'

The Major's brow darkened. 'My dear Bigglesworth,' he said firmly, 'how many times am I to remind you that we are at war? Either we go under, or Germany. The Germans wouldn't die of thirst anyway; they would merely be seriously inconvenienced.'

'But am I not taking enough risks already, without going about blowing things . up?' complained Biggles bitterly. 'It sounds a tall order to me.'

On consideration you may find that it is not so difficult as you imagine. I can supply you with the instrument, a small but powerful bomb-in fact, I brought it with me on the off-chance. You could conceal it in your machine, and hide it when you got back; put it in a safe place until you are ready to use it. Then all you would have to do would be to touch off the time-fuse, set, say, for half an hour, and return to your quarters. That's all.'

all! By Gosh! and enough, too,' cried Biggles. 'All right, sir,' he added quickly, in a resigned tone. 'Get me the gadget and I'll put it in my machine; I'll see what I can do.'

A small but heavy square box was quickly transferred from the back seat of the R.E. 8 to the underseat pocket of the Pup, and Biggles prepared to take his departure. 'It's going to be jolly awkward if the Huns want me to collect information, as I expect they will,' he observed thoughtfully. 'I wish you could arrange for some dummy camps, or aerodromes, to be put up so that I can report - ' He broke off abruptly and stared upwards.

The others, following the direction of his eyes, saw a tiny aeroplane, looking like a silver and blue humming bird, flash in the sun as it turned, and then race nose down towards them.

Biggles recognized the machine instantly, and understood exactly what had happened. '

It's Leffens,' he yelled, 'the cunning devil's followed me. He's spotted me talking to you.

Swing my prop, Algy-quick.'

He leapt into the c.o.c.kpit of the Pup as the silver and blue Pfalz roared overhead, with the pilot hanging over the side staring at them.

In answer to Biggles' shrill cry of alarm Algy darted to the propeller of the Pup, and at the word 'contact', swung it with the ability of long practice. The engine was still hot, and almost before he could jump clear the machine was racing over the sand, leaving a swirling cloud of dust in its wake.

Biggles, crouching low in the c.o.c.kpit, was actuated by one overwhelming impulse as he tore into the air, which was to prevent the Pfalz pilot from reaching Zabala and there denouncing him. That Leffens was flying at such an out-of-the-way spot by pure chance he did not for one moment believe; he knew instinctively that he had been followed, possibly at von Stalhein's instructions-but that was immaterial. The only thing that really mattered was that Leffens had seen him at what could only be a pre-arranged rendezvous with British R.F.C. officers, and he had no delusions about how the man would act or what the result would be. He knew that if he was to continue his work-and possibly the whole success of the British campaign in Palestine hung on his efforts- Leffens must not be allowed to return to Zabala.

Nevertheless, it looked as if he would succeed in getting back, and indeed he had every opportunity of doing so, for his flying start had given him a clear lead of at least two miles. But suddenly he did a curious thing: he turned in a wide circle and headed back towards the oasis. It may have been that he felt safe from pursuit; it may have been that he did not give Biggles credit for acting as promptly as he did; or it may have been that he wished to confirm some detail on the ground. Be that as it may, the fact remains that he turned, and had actually started a second dive towards the oasis when he saw the Pup zooming towards him like an avenging angel. He turned back sharply on his original course and sought to escape, but he had left it too late, for the Pup was slightly faster than the Pfalz.

Biggles pulled up the oil pressure handle of his Constantinesco* synchronizing gear and fired a short burst to warm his guns. His lips were set in a thin straight line, and with eyes fixed on the other machine he watched the gap close between them. He had no com-punction about forcing a combat with Leffens. Quite apart from the fact that the German disliked him, or possibly suspected him, and was therefore a permanent source of danger, he now knew too much. Yet he was by no means a foeman to be despised, for six victories had already been recorded against his name in the squadron game-book**.

Biggles' hand closed over his firing lever, and he sent a stream of bullets down the wake of the fleeing scout. The range was, he knew, far too long for effective shooting, but the burst had the desired effect, and his lips parted slightly in a mirthless smile as he saw the Pfalz begin to sideslip.

'He's nervous,' was his unspoken thought, as he began to climb into position for attack.

But Leffens was looking back over his shoulder and started off on an erratic course to throw his pursuer off his mark. But it availed him little; in fact, in the end such tactics proved to be a disadvantage, for the manoeuvre caused him to lose speed, and with the Pup roaring down on his tail he was compelled to turn and fight.

With the cold deliberation of long experience, Biggles The synchronizing gear for machine-guns which interrupts the firing mechanism ensuring that the bullets do not hit the propeller blades but pa.s.s safely between them.

** Record of all enemy aircraft shot down by squadron members.

waited until he saw the stabbing tongues of flame leaping from the Pfalz's Spandau guns, and then he shoved the joystick forward with both hands. Straight down across the nose of the black-crossed machine he roared like a meteor, and then pulled up in a vertical Immelmann turn*. It was a brilliant move, beautifully executed, and before Leffens could grasp just what had happened the Pup was on his tail, raking the beautifully streamlined fuselage with lead.

But the Pfalz pilot was by no means beaten. He whirled round in a lightning turn and sent a stream of tracer bullets in the direction of the Pup. Biggles felt them hitting his machine, and flinched as he remembered the bomb under his seat, but he did not turn.

The German, unable to face the hail of lead that he knew was shooting his machine to pieces about him, acted with the speed of despair and took the only course left open to him: he flung joystick and rudder-bar over and spun earthward. But if he hoped by this means to throw Biggles off his tail he was doomed to disappointment: not for nothing had his opponent fought half a hundred such combats. The spin was the obvious course, and for a pilot to take the obvious course when fighting a superior foeman is suicidal, for the other man is prepared for the move and acts accordingly.