Colwyn went to bed, but not to sleep. Hour after hour he lay awake, staring into the darkness, endeavouring to put together the facts he had discovered during the afternoon's investigations at the inn. But they resembled those irritating odd-shaped pieces of a puzzle which refuse to fit into the remainder no matter which way they are turned. Try as he would, he could not fit his clues into harmony with the police theory of the murder.

On the other hand, he could not, nor did he attempt, to shut his eyes to the strong case against Ronald, for he fully realised that there was much to be explained in the young man's actions before any alternative theory to that held by the police could be sustained. But so far he did not see his way to an alternative theory. He sought vainly for a foundation on which to build his clues and discoveries; for some overlooked trifle which would help him to read aright the true order and significance of the jumbled assortment of events in this strange case.

In the first place, was Ronald's explanation, about losing his way and wandering to the inn by chance, the true one? The police accepted it without question, but was it likely that a man who was in the habit of taking long walks about the coast would lose his way easily? As against that doubt, there were the statements of the innkeeper and the deaf waiter that they had never seen Ronald before. If Ronald were not guilty, why had he departed so hurriedly from the inn that morning? And if he were not the murderer what was the explanation of the damning evidence of the footprints leading to the pit in which the body of the murdered man had been flung? If the discovery of the two kinds of candle-grease in Mr. Glenthorpe's bedroom indicated that two persons were in the room on the night of the murder, who were those two persons, and what did they both go there for?

He reflected that his only tangible reason, so far, for not accepting the police theory was based on the belief that two people had been in the murdered man's room, and that belief rested on the discovery of a spot of candle-grease which in itself was merely presumptive, but not conclusive evidence. It was necessary to establish beyond doubt the supposition that two people had been in the room before he could presume to draw inferences from it. And, if he succeeded in establishing that supposition, might not Ronald have been one of the two persons, and the actual murderer? What was the significance of the broken incandescent burner, the turned-on gas, and the faint mark under the window?

These questions revolved in Colwyn's head in a circle, always bringing him back to his starting point that the solution of the case did not lie on the surface, and that the police theory could not be made to fit in with his own discoveries. The latter were in themselves internal evidence that the whole truth had not yet been brought to light.

Gradually the line of the circle grew nebulous, and Colwyn was fast falling asleep through sheer weariness, when a slight sharp sound, like that made by turning a key in a lock, brought him back to wide-eyed wakefulness. He sat up in bed, listening with strained ears, feeling for the box of matches at his bedside. He found them, and endeavoured to strike a light. But the matches were war matches, and one after another broke off in his hand against the side of the box. He tried holding the next close to the head, but the head flew off. With a muttered malediction on British manufacturers, Colwyn struck several more in rapid succession before he succeeded in lighting the candle at his bedside. He got quietly out of bed, and, leaving the candle on the table, opened his door noiselessly and looked out into the passage.

He had been put to sleep in a small bedroom in the deserted upstairs wing where the murder had been committed. His room was opposite the lumber room, which was three doors away from the room in which the body of the dead man lay. When the question of accommodation for Superintendent Galloway and himself had been discussed, the former had chosen to have a bed made up in the bar parlour downstairs as more comfortable and snug than any of the bedrooms upstairs, but Colwyn had consented to sleep in the deserted wing. The innkeeper, who had lighted him upstairs, had apologised for the humble room and scanty furniture, but Colwyn had laughingly accepted the shortcomings of the room as a point of no importance, and had stood at his door for some moments watching a queer effect in shadows caused by the innkeeper's candle throwing gigantic wavering outlines of his gaunt retreating figure on the bare stone wall as he went down the side passage to his own bedroom.

Colwyn, looking out into the passage, could hear or see nothing to account for the sound that had startled him into wakefulness. The candle by his bedside gave a feeble glimmer which did not reach to the door, and the passage was as dark and silent as the interior of a vault. The stillness and blackness seemed to float into the bedroom like a cloud. But he was certain he had not been mistaken. A door had been unlocked somewhere in the darkness, and it had been unlocked by human hands. Who had come to that deserted wing of the inn in the small hours, and on what business? He decided to explore the passage and find out.

He left the door of his room partly open while he donned a few articles of clothing, and pulled a pair of slippers on his feet. He glanced at his watch, and noted with surprise that it wanted but a few minutes to three o'clock. He extinguished his candle and, taking his electric torch, crept silently into the passage.

He recalled the arrangements of the rooms as he had observed them the previous afternoon. There were three more bedrooms adjoining his, all empty. On the other side of the passage was the lumber room opposite, next came the room in which Ronald slept, then the dead man's room, and finally the sitting-room he had occupied. The door of the sitting-room opened not very far from the head of the stairs.

Colwyn first examined the bedrooms on his side of the passage, stepping as noiselessly as a cat, opening and shutting each door without a sound, and scrutinising the interiors by the light of his torch. They were empty and deserted, as he had seen them the previous afternoon. On reaching the end of the passage he glanced over the head of the staircase, but there was no light glimmering in the square well of darkness and no sound in the lower part of the house to suggest that anybody was stirring downstairs. He turned away, and made his way back along the passage, trying the doors on the other side with equal precaution as he went. The first three doors—the sitting-room, the murdered man's bedroom, and Ronald's bedroom—were locked, as he had seen them locked the previous afternoon by Superintendent Galloway, who had carried the keys away with him until after the inquest on the body.

The lumber room at the other end of the passage had not been locked, and the door stood ajar. Colwyn entered it, and by the glancing light of the torch looked over the heavy furniture, mouldering linen, and stiffly upended bedpoles and curtain rods which nearly filled the room. The clock of a bygone generation stood on the mantel-piece, and the black winding hole in its white face seemed to leer at him like an evil eye as the light of the torch fell on it. But nobody had been in the room. The dust which encrusted the furniture and the floor had not been disturbed for months.

Colwyn returned, puzzled, to his own room. Could he have been mistaken? Was it possible that the sound he had heard had been caused by the door of the lumber room swinging to? No! the sound had been too clear and distinct to admit the possibility of mistake, and it had been made by the grating of a key in a lock, not by a swinging door. He stood in the darkness by his open door, listening intently. Several minutes passed in profound silence, and then there came a scraping, spluttering sound. Somebody not far away had struck a match. Looking cautiously out into the passage, he saw, to his utter amazement, a gleam of light appear beneath the door in which the dead man lay. The next moment the gleam moved up the line of the door sideways, cutting into the darkness outside like a knife. The gleam became broader until the whole door was revealed. Somebody inside was opening it. Even as he looked a hand stole forth from the aperture through which the light streamed, and rested on the jamb outside.

Colwyn was a man of strong nerves, but that sudden manifestation of light and a human hand from a sealed death chamber momentarily unbalanced his common sense, and caused it to swing like a pendulum towards the supernatural. He would not have been surprised if the light and the hand had been followed by the apparition of the murdered man on the threshold, demanding vengeance on his murderer. The feeling passed immediately, and with the return of reason the detective stepped back into his room, closed his door quietly, and watched through a knife's edge slit for the visitor to the death chamber to appear.

The door of the dead man's room opened gently, and the face of the innkeeper's daughter peered forth into the darkness, her impassive face, behind which everything was hid, showing like a beautiful waxen mask against the light of the candle she held in her hand. Her clear gaze rested on Colwyn's door, and it seemed to him for a moment as though their glances met through the slit, then her eyes swept along the passage from one end to the other. As if satisfied by the scrutiny that she had nothing to fear, she stepped forth from the death chamber, closed and locked the door behind her, withdrew the key, walked swiftly along the passage to the head of the stairs, and descended them.

Colwyn opened his door and followed her. He paused outside to pick up the boots which he had placed there to be cleaned, and carrying them in his hand, ran quickly to the head of the stairs. Looking over the landing, he saw the girl reach the bottom of the stairs and turn down the passage towards the back door, still carrying the lighted candle in her hand.

When Colwyn reached the bottom, the girl and the light had disappeared. But a swift gust of wind in the passage revealed to him that she had gone out by the back door, and closed it after her. He followed along the passage till he felt the latch of the back door in his hand. The door yielded to the lifting of the latch, and he found himself in the open air.

It was a grey northern night, with a bitter wind driving the sea mist in billows over the marshes, and a waning half moon shining fitfully through the dingy clouds which scudded across a lead-coloured sky. By the light of the moon he saw the figure of the girl, already some distance from the house, swiftly making her way along the reedy canal path which threaded the oozing marshes.

Colwyn was not a stranger to marshlands. He had waded knee-deep from dawn to dusk through Irish bogs after wild geese; he had followed the migratory seafowl of Finland, Russia and Serbia into their Scottish breeding haunts, and he had once tried to keep pace with the sweep of the Bore over the Solway Marshes, but he had never undertaken a task so difficult as following this girl across a Norfolk marshland. The path she trod so unhesitatingly was narrow, and slippery, with the canal on one side and the marshes on the other. In keeping clear of the canal Colwyn frequently found himself slipping into the marshes. His feet and legs speedily became wet and caked with ooze, and once he nearly lost one of his boots, which he had pulled on hurriedly outside the inn, and left unlaced.

But the girl walked straight on with a swift and even gait, treading the narrow path across the morass as securely as though she had been on the high road. Colwyn soon realised that the path they were following was taking them straight across the marshes to the sea. The surging of the waves against the breakwater sounded increasingly loud on his ears, and after a while he saw the breakwater itself rise momentarily out of the darkness like a yellow wall, only to disappear again. But presently it was visible once more, looming out in increasing clearness, with a ghostly glimmering of the grey waters of the North Sea heaving turbulently outside.

As they neared the breakwater the path became drier and firmer, and the light of the moon, falling through a ragged rift in the scurrying clouds, showed a line of sand banks and strips of tussock-land emerging from the marshes as the marshes approached the sea.

The girl kept on with the same resolute pace, until she reached a spot where the canal found its outlet to the sea. There she turned aside and skirted the breakwater wall for a little distance, as if searching for something. The next moment she was scaling the breakwater wall. Colwyn was too far away to intercept her, or reach her if she slipped. He stopped and watched her climb to the top of the wall, and stand there, like a creature of the sea, with the spray leaping hungrily at her slight figure. He saw her take something from the bosom of her dress and cast it into the wild waste of seething waters in front of her. Having done this she turned to descend the breakwater. Colwyn had barely time to leave the path, and take refuge in the shadow of the wall, before she reached the path again and set out to retrace her steps across the lonely marshes.