“What’s that?” asked Frank, as he gazed across the water.

“Smoke,” replied Jack. “It’s plain enough.”

“I know that,” replied the former, “but what I meant is, do you suppose it is a battleship?”

“Looks like it might be,” replied Jack briefly.

“Russian or German?” asked Frank.

“Can’t tell,” said Lord Hastings, who had been peering at the cloud of smoke through his glass. “I can make out that it is a battleship, but that’s all. However, we shall know soon enough.”

Slowly the cloud of smoke came nearer and nearer, until at last the dim outline of a large battle cruiser of the second class was plainly visible to the naked eye. But still those aboard the D-16 were unable to make out her nationality, for she flew no flag.

“We’d better get ready to dive in case she proves to be a German,” said Lord Hastings.

“Right you are, sir,” replied Jack, and turning, went below.

Frank and Lord Hastings remained upon the bridge.

Now, of a sudden, there came a faint “boom” across the water.

“Can she have sighted us, sir?” asked Frank anxiously. “Had we not better dive at once?”

“No, I don’t think she has sighted us,” replied Lord Hastings.

“Then what is she shooting at?”

“You’ve got me. But that is what we shall have to find out.”

Lord Hastings went below, where he ordered the course of the D-16 altered slightly, so as to bring her closer to the far side of the distant cruiser. Then he returned on deck.

Time after time the boom of the big guns could be heard, and those aboard the D-16 were at a loss to make out what the cruiser was firing at. Not another speck was visible on the broad expanse of the Baltic Sea.

“There must be something wrong,” said Lord Hastings. “But I can’t imagine what——Hello, she’s hoisting her flag.”

“Can you make it out, sir?” asked Frank.

Lord Hastings looked long and carefully through his glass.

“Russian,” he said at last.

“Good,” exclaimed Frank. “We are among friends at any rate.”

“I wouldn’t be too sure,” said his commander. “It may be a German ship that has hoisted the Russian flag for a purpose.”

“Well, we’ll soon see now,” said Frank.

Now the submarine had approached so close that Lord Hastings deemed it advisable to submerge, so that the vessel might not be seen. This was done, and standing at the bottom of the periscope below, the commander of the D-16 took in the scene about him.

Occasional clouds of smoke issued from the cruiser, indicating that her guns were still in action, but for the life of him Lord Hastings could not make out the object of her shots. Also, the cruiser was maneuvering in a strange way, and Lord Hastings could not account for this either.

He stepped aside and Jack took a look through the periscope. Peering long and carefully, he stepped back suddenly with a cry.

“What’s the matter?” asked Lord Hastings.

“I’ve made out the cause of the trouble, sir,” said Jack.

“What is it?” demanded his commander.

“Why, sir,” replied the lad, “the cruiser is being followed by a submarine—I can just make out her periscope in the distance. That’s what the cruiser is firing at. And her strange maneuvering is caused by the fact that she is trying to escape torpedoes. So far she must have been successful.”

“In that event,” said Lord Hastings, “it is up to us to lend the cruiser a hand. Signal full speed, Mr. Templeton.”

Jack obeyed, and the swift British submarine dashed madly through the water.

Suddenly Jack, who was at the periscope, perceived a puff of smoke issue from the forward turret of the cruiser, and a moment later a shell plowed up the water near the D-16.

“We’ll have to submerge at once, sir,” he said. “The cruiser has sighted us and takes us for an enemy. One of those shells may hit us.”

“All right,” said Lord Hastings. “First let me have a look.”

He stepped to the periscope, which Jack relinquished to him, and peered ahead. Beyond the cruiser he could make out the periscope of another submarine. Calculating the distance. Lord Hastings gave the order to submerge four fathoms.

Then the D-16 dashed in the direction of the submarine that was seeking to destroy the Russian.

Running at 30 knots, the D-16 soon came upon its prey. A dim bulk suddenly loomed up ahead, some distance higher in the water.

“It’s the enemy,” said Frank, after a careful scrutiny.

“All right,” said Lord Hastings. “Give her a shot before she discovers our presence. We can’t miss at this distance.”

Through the heavy glass in the bow of the submarine Frank watched the effect of the shot. The German submarine staggered suddenly in her stride, then, without a sound, disappeared from sight.

Frank returned to Lord Hastings’ side.

“She’s gone, sir,” he said quietly.

Lord Hastings turned to Jack.

“We’ll go to the surface at once,” he said.

Hardly had the D-16 bobbed up from beneath the water, when there was a loud boom from the Russian ship now but a short distance away, and a shell screamed overhead.

“Run up the British flag, quick, Mr. Templeton,” ordered Lord Hastings.

A moment later the Union Jack fluttered aloft.

Came another shot from the Russian, and a second shell screamed near.

“The fools,” cried Lord Hastings angrily. “What do they mean by that?”

“They think we are trying a ruse to get near them, I suppose,” replied Frank. “They are unable to tell we are not the same submarine that followed them.”

“True,” said his commander, “I hadn’t thought of that. But how are we to let them know who we are?”

“Well, my idea would be to run up a flag of truce,” said Frank. “Then we can explain.”

“Good,” exclaimed Lord Hastings. “Run up a flag of truce at once.”

It was the work of but a few seconds to raise a white flag, and when it had straightened out before the brisk breeze, there was no further shot from the Russian cruiser.

Soon a boat put over the cruiser’s side, and manned by a well armed crew, came toward the D-16. Within hailing distance an officer arose and cried out something in a tongue unintelligible to any on board.

“Speak English!” Lord Hastings called back. “I can’t understand you.”

The next words came in halting English.

“Who are you?”

“British submarine, D-16!” Lord Hastings called back.

“Then why did you fire at us?”

“We didn’t. You were fired upon by a German submarine, which we have just sunk. Will you come aboard?”

“Yes,” was the reply, and the little boat drew closer.

A moment later a man in the uniform of the Russian navy stepped over the side and advanced toward Lord Hastings.

“Are you the commander of this vessel?” he asked.

Lord Hastings bowed.

“I am,” he replied.

“Then I demand to know, as you claim, and appear, to be English, why you fired upon us?”

“I told you,” said Lord Hastings quietly, “that we did not fire upon you. You were attacked by a German submarine, which we have just had the pleasure of sending to the bottom.”

The Russian officer looked skeptical.

“May I ask to see your papers?” he asked.

“You may,” replied Lord Hastings, now somewhat nettled, “but you won’t.”

“In that event,” replied the officer, “I must place you under arrest.”

Lord Hastings smiled sardonically.

“Which would be quite a task,” he said. “Remember, you are aboard my ship now, and if I choose, I can have you thrown into the sea. However, as there seems to be some misunderstanding, I am ready to accompany you aboard your ship, where I shall explain matters to your commander.”

The officer could but be satisfied with this.

“Very well,” he said.

Lord Hastings turned to Jack.

“You shall go with me,” he said. “Frank, you remain here.”

He stepped into the boat and Jack and the Russian officer followed him. The boat put off toward the Russian cruiser.

Aboard the cruiser Lord Hastings was at once ushered into the presence of the Russian commander, Captain Bergoff. To him he told the same story he had related to his officer.

“Then how did you get in the Baltic Sea?” asked the Russian officer.

“Through the Kiel canal,” replied Lord Hastings.

The Russian commander smiled.

“And you expect me to believe that?” he said. “Impossible.”

“Nevertheless,” said Lord Hastings, drawing himself up, “it is true.”

“I won’t dispute you,” was the reply. “Have your own way. However, I fear that I must place you under arrest.”

“Under arrest!”

“Yes. I have no doubt that you are English, but I believe you are traitors to your country. Your speech proves you are English, but it would be impossible for a British vessel to force a passage of the Kiel canal. I suppose you will tell me, however, that you sank several German vessels there.”

“We did,” replied Jack, breaking into the conversation for the first time.

Again the Russian smiled.

“And here seem to be two full grown men asking me to believe a thing like that,” he said. “It’s too much. Lieutenant!”

The officer who had escorted the two aboard approached.

“Have them confined in irons,” was the command.

“But,” protested Lord Hastings, “regardless of our nationality, we came here under a flag of truce.”

“Spies in British uniforms,” said the Russian sternly. “You will leave here under the Russian flag and in irons.”