THE LONE HIKER seemed to have the world to himself. Behind him the little town of Benham, which he had left half an hour before, was now out of sight beyond the friendly bulk of the last trees to be seen for some time.

To the right, half a mile distant, but drawing closer with each stride he took, was the North Sea. Away to the left was the rolling heath country that marched into the west.

Ahead of him was a lonely, sandy waste of country, known as Little Sahara to the people of that part of Suffolk, and the hiker knew that for the whole sixteen miles which he must cover across it, only one thing would break the naked line of sand and sea. That was a gaunt and deserted Martello Tower which he had been told marked the half-way distance.

But this lonely prospect did not seem to dismay the man. He sniffed the strong air appreciatively as, before leaving the last bit of green turf for the rough track that would be his way, he paused to fill his pipe.

Outlined against the sky, he made a strange figure for that remote spot. He was dressed in khaki shirt and shorts, golf stockings and heavy boots, and to top the outfit, as if in gay salute to the wild places he was traversing, he wore a brilliant green beret. On his back was the inevitable rucksack and in one hand he carried a staff or walker’s thumb-stick.

He started on again, his mind busy with his own thoughts, his eye registering each change in the general prospect. It was without the slightest foreboding that he went plodding across that barren land which had been so aptly named Little Sahara. There was no clairvoyant quality about it to whisper that the Martello Tower, whose only significance to him was, so he thought, that it marked the course, would be the last thing that he would ever see.

Owing to the rolling nature of the sand, piled into dunes and little valleys by the savage winter winds that drive in from the North Sea, he did not catch the first glimpse of the tower until he had covered several miles.

He spied it then as a low, round stump, squatting close to the horizon, and, as he viewed it, seeming to rise right out of the sea. But as he advanced, it rose slowly out of its bed until he could see almost the whole round unlovely structure that had been reared back in the time when Napoleon swore to invade England—and learned that vows do not conquer a nation.

He paused again and knocked his pipe against his heel. Then he took a slow, deliberate view of his surroundings.

The sun was hot on his back, even though it was autumn. Only the lightest of breezes drifted in from the sea. It was more like a day that summer had forgotten.

Yet in the midst of all this quiet and brightness there swept over him a feeling of such sharp depression that the physical revulsion forced him into speech.

“What the devil’s the matter with me?” he apostrophised a wheeling gull. “Here it is, the finest day I’ve seen this year, and not a thing but me and all outdoors, and yet, hang it, I feel as if some one was standing behind me with a bludgeon.”

He actually turned to peer about. A gull swooped nearer, screamed in derision, and soared out over the sea. The man recov-ered his good spirits and laughed.

“I’ll be seeing pictures next,” he told himself. “What I need is a spot of food and a swig out of the flask. It’s not more than a mile to the old tower, and it’ll be nice and shady inside. Forward, my jolly old hiker.”

With that, he made to start on again, but as he did so his eye caught something that made him pause.

“Now what was that?” he muttered.

Low down against the sand something had moved. To the man who stood gazing across the sand, it had seemed at first like a bird vanishing into one of the myriad hollows.

Then reason told him it could not be a gull, for the object had appeared black, and no other sort of bird was visible. He hadn’t seen a crow in miles.

Another movement caught his eye, this time a little distance from where he had seen the other. He was able now to take more note of its size and form, and to his puzzlement found it could be likened to nothing more than a human head adorned by a cap.

But if this were so then the head must be attached to a body, and the same line of deduction indicated that some one must be crawling along between the dunes.

It was a conclusion that seemed ridiculous. Why should any one choose to move in such surreptitious fashion in this deserted spot? It wasn’t as though it were the hour and place for wildfowl. There wasn’t one to be found within miles. In the first hours of dawn, farther on, where the muddy creeks cut into the coast, it would be different; but not here.

He saw the movement again, and he knew that, strange though it might seem, the moving speck was indeed a man, and that for some reason or other he was trying to conceal his progress across the sand.

He suddenly realised how plainly visible he himself must be. Indeed, his solitary figure must stand out against that denuded background almost as clearly as the Martello Tower.

Ordinarily he would have trudged on quite openly, but there was something so furtive about the actions of the other man that he was curious to know the reason. He could not be sure, but it seemed to him that the fellow’s course was gradually converging on the Martello Tower.

A deep hollow between two dunes gave him the chance he sought. He sank down, eased his rucksack from his shoulder and peered over the top.

Minutes passed. Not a thing moved. An Arab of the real Sahara could not have vanished more completely than the figure he had seen. The only thing that reached him was an increased heaviness of spirit which he found impossible to understand or to shake off.

At the end of a quarter of an hour he rose, and giving his broad shoulders a shake as if to rid himself of the invisible load of de-spondency, slung the rucksack into place and strode on purposefully. If there was anything there he would find it on closer ap-proach.

But nearer and nearer though he drew to the tower, not a moving object could be seen except the gulls that wheeled and dipped overhead, berating him, it seemed, for this invasion of their solitude.

He changed his course a little so as to bring him round towards the low entrance, from which he could now see a dilapidated door hanging. He approached it in a direct line, and, when he was a matter of some thirty or forty yards away, could see right into the gloom of the interior. But no detail was visible; only a well of heavy twilight.

Then suddenly he paused. Something emerged from the gloom and appeared in the frame of the doorway. At least, it seemed to the hiker that a human form hovered there for a brief moment be-fore becoming part of the heavy curtain behind.

In any ordinary habitation or building there would have been no sinister suggestion about that fleeting vision. But here, in the broad daylight of this sunny day, in this expanse of utter loneliness, there was something deeply disturbing to the solitary watcher in this furtive movement.

Was it the man whom he had seen before? Or had there been more than one individual creeping through the hollows? Had they reached the tower? Why this surreptitious stalking of some one or something? Was he the quarry? Or was it another whom he hadn’t yet discovered?

Whatever the purpose, the watcher saw nothing else as he drew still nearer. He told himself that the prowler he had discovered was no more than some vagrant who had viewed his approach with natural suspicion. He broke into a whistle as he began to feel for the straps of his rucksack. He was thinking that he had been a bit of an old woman to imagine some trick of light and shadow to possess a sinister meaning.

He was close to the door now, and suddenly he saw something move against the twilight. He hesitated on the threshold. The warning in his subconsciousness was so urgent that it was like an invisible hand pressing him back.

He peered into the gloom, but nothing moved. Then he gave voice. “Hallo, inside!”

The echoes came back to him muffled; not another sound. He frowned and started forward again. One foot went over the sill, but he never completed the crossing of that threshold alive.

Out of the gloom on either side of the door shadows came upon him, and something descended heavily upon his skull.