During the latter part of her voyage, the "Harlech" was not able to travel faster than eight knots an hour, whereas normally she was capable of doing as much as thirteen under favourable conditions. The truth was her engines had been badly damaged by shell fire; and had she not been commanded by a man of inflexible resolution, there is no doubt she would have put into one of the Irish ports for safety and repairs. Crouch, however, had his orders, and these were to take the ship to Portsmouth, with as little delay as possible and in face of every risk; and thither he was determined to go.

It was not until the evening upon which they sighted the Fastnet light that Crouch himself, for the first time, had some cause for suspicion in regard to Rudolf Stork. The man's conduct on that particular occasion was by no means easy to explain.

During the incident with the "Dresden" two of the ship's quartermasters had been severely wounded and rendered incapable of carrying on their work. On ocean liners and merchant vessels the quartermasters are entrusted with a very important office: it is they who take their turn, watch by watch, at the wheel, who are responsible that the ship maintains her course. There were now but two quartermasters capable of doing duty; and Captain Crouch had to look about him to find other men capable of taking the places of those who had been disabled.

It so happened that Rudolf Stork was one of the first to volunteer, and was able to prove that he had sufficient knowledge of a ship's compass to take charge of the wheel. He was told off for the middle watch, which was that commanded by the chief officer, Mr. Dawes.

Having picked up the famous Fastnet light, and verified his course, which was almost due south-east to the Scillies, Captain Crouch turned in at midnight, at the end of his own watch, and handed over to Dawes, who ascended the bridge steps followed by Stork. The night was bitterly cold; a fine rain was driving south-westward, down the St. George's Channel. There was also a sea fog which completely obliterated the moon and stars. Both Dawes and the acting quartermaster wore waterproof coats and sou'westers.

Now, it so happened that on this occasion the chief officer was very far from well. A few days before, he had contracted a violent cough which that night showed signs of becoming serious. He had reported to the captain that he felt indisposed, but protested that he was quite able to do his duty. For all that, he had not been upon the bridge three-quarters of an hour when he was seized with an immoderate fit of coughing. This coughing was not only a serious impediment to the proper carrying out of his duty, but it was also exceedingly painful. His pulse was exceptionally fast, and a certain hot dryness of the skin was a sure symptom of fever. Indeed, had there been a doctor on board, he would have diagnosed the case at once, and pronounced the chief officer to be on the verge of double pneumonia, aggravated by bronchial trouble. In face of this, it speaks volumes for the pluck and perseverance of Mr. Dawes that he had undertaken to go on watch at all.

Very soon, however, the coughing became so violent and persistent that he was, at last, obliged to leave the bridge, to go below to his cabin. He was not absent much longer than ten minutes; but, it so happened that, whilst he was away, Crouch, who had not yet been to sleep, returned to the bridge.

The captain did not ascend the steps that led from the main-deck, but came upon the wheel from the after side, by way of the boat-deck, which had been much shattered by the shell fire of the "Dresden." Crouch--as is well known--had the eye of a lynx; and he saw at once that Stork was holding the ship on a course at least twenty-five degrees south of that marked upon the captain's chart.

"Hullo there!" he shouted, so suddenly that Stork started and let out an exclamation of surprise.

The man was obviously alarmed, and for a moment lost his self-possession, but recovered himself in an instant, and put the ship about upon her proper course.

"Look here," said Crouch, "I'll have no monkey tricks on board this packet. What d'ye mean? Answer me that! What d'ye mean?"

Stork made some feeble excuse, to which Crouch listened in stony silence. When Mr. Dawes returned to the bridge, he found his captain in none of the best of tempers. Neither was Crouch much inclined to be sympathetic in regard to the chief officer's hacking cough.

"You're ill, man," said he; "of course, you're ill. I know that as well as you; and as I told you before, you were in no fit state to come on duty. Still, if you undertake a job of work, I expect you to do it; and it is not for me to tell you a ship's officer's duty. As long as you hold the bridge, you remain there. Understand this, Mr. Dawes: there's a mighty difference between a ship crossing the Atlantic in time of war, with such a cargo as we shipped in New York harbour, and an oil-tank steamer in the south Pacific, when the captain and the mate can play halfpenny nap all day and sleep like infants half the night. If you're not fit for duty, go below, sir, and leave the bridge to me. It won't be the first time in my life I've done eight hours on end."

Mr. Dawes took the hint, which, indeed, he was hardly in a condition to reject. He went below, still coughing and more than a little ashamed.

As for Crouch, he remained on duty until eight bells had sounded, which--as the conclusion of the middle watch--is four o'clock in the morning. Throughout that time, he kept the eye of a hawk upon the man at the wheel, who, in his turn, never once looked up from the compass.

All this while, Crouch's brain was active. He may have been inclined to be pig-headed, but he was by no means a fool. For the first time, he found himself wondering whether there was any truth in what Jimmy had told him. He was perfectly convinced that Stork had changed the course of the ship on purpose. The man was not only quite thorough in his work as a rule, but understood his duty, and was hardly likely to have made so serious a mistake through negligence alone.

When the last watch came to deck, the captain's eyes followed Stork as he made his way to the forecastle; and then he, too, went below to his cabin, to snatch a few hours' sleep. He was now quite ready to admit the possibility that he had made a serious mistake, and made up his mind to keep a sharp eye upon Stork throughout the remainder of the voyage.

The next day--when the "Harlech" was steadily ploughing her way, heading for the entrance of the Channel--was an anxious time for Crouch. He knew the full value of the cargo he carried, and its utmost importance to those to whom it was consigned; and he knew also that, at any moment, a torpedo from some lurking, hidden foe might send the ship and all on board to the bottom. A heavy sea fog lay upon the surface of the water. Dawes was in bed, unable to rise; and since the third officer was somewhat young and inexperienced, nearly all the responsible work of the ship devolved upon the captain.

That afternoon, towards sunset, the fog lifted a trifle. Crouch remained upon the bridge, straining his single eye through his long telescope for minutes at a time. Presently, he closed the instrument with a snap, tucked it under his arm, and dived both hands into his trousers pockets.

"Just as I thought!" he exclaimed. "We're a good six points to the south, and on the wrong side of the Scillies. That man's a rogue."

There was no one to hear this remark but the quartermaster at the wheel, and Jimmy Burke, who had just then ascended the bridge steps with a cup of bovril for the captain, who had sent below for something to warm him up.

"My boy," said Crouch, "I may have done you a wrong. Mind, I don't say I have; but, I'm quite ready to confess that there's a chance of it. Come and see me in my cabin, at ten o'clock to-night."

During that evening and the early hours of the night, the "Harlech" rounded the Scilly Islands, and sighted the Cornish coast, where the great, powerful light at the Lizard flashes its message of warning across eighty miles of sea.

Jimmy Burke, filled with anticipation concerning his coming interview with the captain, did not turn into the forecastle, but betook himself to the poop, where he lay down upon a great coil of rope.

Now, those who know anything of the hardships of a sea-faring life are well aware that a coil of rope makes a couch that is far from being uncomfortable--as things go with those whose fate it is to serve before the mast. There is always a great depression in the middle, in which it is possible for the body to sink; and this is exactly what happened to Jimmy Burke. He sank so deeply in the midst of the coils of rope that, in spite of the fact that it was an exceedingly bright moonlit night, his form was completely hidden from any one who might happen to be passing.

He did not fall asleep, because he was particularly anxious to count each sounding of the ship's bells, knowing that at four bells precisely he would have to report himself to Captain Crouch. He was therefore in full possession of his senses and wide awake when a shadowy form ascended the poop steps, and passed to the taffrails at the very stern of the vessel, from which was suspended the rope of the ship's log.

This man Jimmy recognized at once as Rudolf Stork. Even in that light, there was no mistaking his broad, sloping shoulders and his slovenly gait. Stork carried something in his hand; and at first the boy was not able to make out what this was. He was not left long in doubt, however; for, when Stork raised it to the level of the taffrails and began to move up and down a small lever which made a persistent, irregular tapping sound, it became manifest that the man was in possession of a signalling lamp, with which he was sending messages to some unknown point in the darkness that was spread upon the sea.

Jimmy Burke was like one transfixed. He remained motionless and breathless, amazed at the man's audacity. And before he had time to put two and two together, to realize the full import of what was happening, four bells sounded from the forward part of the ship. It was ten o'clock; Jimmy was expected in the captain's cabin.

Swiftly and silently, the boy got to his feet. As he did so, fearing that his presence might be discovered, he kept an eye upon Stork, whose back was turned to him, whose attention was fully occupied with the work he had in hand. On the surface of the water, in the white wake of the ship, Jimmy could see the reflection of the signalling lamp that flashed and flickered with the dots and dashes of the Morse code, as if, in its own poor way, it strove to imitate the magnificent lighthouse that lay but a few miles to the north.

And then, on a sudden, from out of the darkness, like an evil eye in the night, there appeared an answering light--small, far away, and yet marvellously distinct.

Jimmy drew back in horror. For all that, he remained sufficiently master of himself to keep absolutely silent. Without a sound, he glided down the companion-ladder to the well-deck, reached the main-deck, and burst into the captain's cabin.

He had not troubled to knock; and his abrupt entrance caused Crouch to look up from a volume of sailing instructions he had been in the act of reading.

"My lad," said he, "we're not over particular here in regard to manners; but, it's customary to ask permission to enter the captain's cabin."

Then he saw that the boy's face was ashen white, and shaped his lips as if about to whistle.

"What's up?" said he. "What's up?"

"For mercy's sake," cried Jimmy, "come with me! That villain is signalling from the poop to a German submarine."

Crouch straightened like a man struck. For fully a minute, he stared at Jimmy in amazement. There was that in the expression of the boy's face that left no room for doubt. No one--and Captain Crouch less than any one--could fail to see that he had spoken what he honestly believed to be the truth.

"A German submarine!" repeated Crouch.

"What else could it be?" cried Jimmy. "No cruiser, gunboat or destroyer would dare to show up so far from home. It's a submarine, sir, sure enough. And the rascal's signalling with a shuttered lantern in the Morse code, and they have answered back."

Crouch moved quickly to the doorway, and then, coming back into the room, flung open a drawer in his writing-desk, and took out a small, nickel-plated revolver that glittered in the lamplight.

"We'll put a stop to this," he cried. "It may not be too late to save the ship." Followed by the boy, he dashed out upon the deck.

There are scenes in the lives of us all which impress us so vividly at the time that we carry them with us always in our memory, as clearly and as permanently as an impression can be made upon a photographic plate.

Jimmy Burke will never forget the moonlit scene that was presented to his view from the doorway of Captain Crouch's cabin, that was at once beautiful and terrible. On the starboard side of the ship the rocks of Cornwall arose from out of the sea in a long, dark, rugged line, in the centre of which the Lizard light flashed like a brilliant star. A full moon hung low in the heavens, tracing a broad, silvery pathway across the broken surface of the sea. The "Harlech" was moving cumbrously through the water, on a course almost due east, when, on a sudden, in the full light of the moon, there rose out of the water, like some hideous monster of the under-sea, the periscope and conning-tower of an enormous submarine, upon the side of which was just discernible the ominous and dreaded letters--U93.