to pass on their way.

"And now where do you wish to go, Mr. Cushing?" Dave inquired, after they had passed the British provost guard.

"I suppose you expect me to search for the thief," rejoined the man from the State Department. "But that would now be worse than a waste of time. Gibraltar, quaint Moorish city that it is, is so full of holes in the wall that it would be impossible to find the thief, for he will not venture out again to-night. The best thing I can do will be to go straight to the American admiral, and you gentlemen, I imagine, can take me there."

"A launch will put off from the mole for the flagship at ten o'clock," Dave informed him. "We may as well go down to the mole and wait."

Twice, on the way, after leaving the more crowded parts of the city behind, the three were challenged by English sentries invisible in the darkness.

"Who goes there?" came the sentry's hail in each instance.

"Officers from the American flagship," Darrin answered for the party.

"Pass on, gentlemen," came the response out of the darkness.

At all times strict watch over all comers outside the British army service is kept at Gibraltar, and after dark this vigilance is doubled.

"On a moonless night like this, one would imagine that Gibraltar, save for the few blocks of 'city,' held few human beings," murmured Dan, as the three continued on at a quiet walk toward the water front. "One gets the impression that there are but a few sentries, sprinkled here and there, yet we know there are thousands of British soldiers scattered over this rock."

"Hardly scattered," smiled Dave Darrin. "Except for the guard, men and officers are alike in barracks, and many of the barracks are at rather long distances from the fortifications."

Nor are the fortifications to be found along the water front. Back on the great hill of rock are gun embrasures, often cut into the face of the rock itself. Back of the embrasures are galleries cut through the stone, and here, in time of siege, the soldiers would stand behind the huge guns.

Gibraltar's harbor is small, though large enough to hold a great fleet. In the days when cannon had shorter range than now, a British fleet might have hidden in the harbor and been secure against all the fleets of the world, for the guns of the huge fortress could have sunk the combined navies of the world, had they attempted to enter the harbor. In these modern days Gibraltar is not so secure, for the heights of Algeciras, in Spain, are only about seven miles away. If Spain were at war with Great Britain, or if any other power took the heights of Algeciras from Spain, guns could be mounted on those heights that would dominate the harbor of Gibraltar. None the less, as long as war exists and the huge stone height of Gibraltar remains, the impression of strong military force will abide with the rock.

Down at the mole a British sentry stopped the trio. Near him stood a corporal and three other soldiers.

"American officers and a friend," replied Ensign Darrin, when halted by this sentry. Then the trio advanced when ordered. Lieutenant Totten, from the 'Hudson,' stepped forward, peered at Darrin and Dalzell, and said to the corporal:

"I recognize these gentlemen as officers of ours."

"And the friend?" inquired the corporal.

"The friend is an American citizen who has business with Admiral Timworth," Dave stated.

"Then it is all right," Lieutenant Totten assured the corporal.

Whereupon the British corporal permitted Cushing to step out on the mole with his companions, Darrin and Dalzell.

"Which is the flagship launch?" asked Darrin.

"The rearmost," answered Lieutenant Totten. "Ours is the only launch here. The two other launches belong to the warships of other powers."

Cushing, while this brief conversation was going on, had walked rapidly along the mole until he reached the farthest launch.

"I want you!" he shouted, bending over suddenly.

He had found and seized by the coat collar the man with the green hat.

Dave and Dan rushed to the spot, hardly knowing what they could do, as they did not want to see the representative of the American State Department lack for backing.

"Pull Cushing away from that fellow," ordered Totten.

"Is that an official order?" Dave flashed back, in a whisper.

"It is," nodded Totten, and faded back into the blackness of the night.

Dave bounded forward. He saw that the launch was one belonging to some liner or merchant ship in the harbor. Three or four men belonging in that launch had leaped to the rescue of Mr. Green Hat. Dave, with one tug, tore Cushing away.

Mr. Green Hat fell back in the launch. Two sailors belonging to that craft cast off the lines at bow and stern, and the launch glided out into the harbor.

"Why didn't you help me, instead of putting the double cross on me?" Cushing demanded, angrily.

"I had my reasons," Ensign Darrin replied, briefly.

"They must have been good ones," muttered Cushing.

"All aboard for the flagship!" announced Lieutenant Totten, in a quiet tone.

"Come along, if you're going out with us," Darrin urged Cushing.

The passengers for the flagship launch were speedily aboard. Other officers were there who had been ashore for the evening.

As the launch was cast off she glided almost noiselessly across the smooth water of the harbor, followed closely by the shifting rays of a British searchlight on shore. Ever since the great European war had started searchlights stationed on shore had followed the movements of every craft in the harbor at night. Beyond, the flagship's few lights glowed brightly. In a few minutes the party was alongside.

Dave and Dan, after saluting the officer of the deck, and reporting their presence on board, went at once to Dave's quarters.

"There was a good deal of a mix-up, somewhere," Dan announced, at once. "Why should Totten order you to drag Cushing away from Mr. Green Hat, when that rascal had robbed Cushing of valuable government papers?"

"It's too big a puzzle for me," Ensign Darrin admitted, promptly. "But Lieutenant Totten is my superior officer, and the responsibility belongs to him."

For a few minutes the two chums chatted. Dalzell was about to say good night and go to his own quarters, when an orderly rapped at the door, then entered, saluting.

"The admiral's compliments, gentlemen," said the messenger. "The admiral wishes to see Ensigns Darrin and Dalzell at once."

"Our compliments, and we will report at once," Dave answered. Both young officers were now in uniform, for Dan had left his in Dave's quarters before going ashore, and the chums had changed their clothes while chatting. It now remained only for Dave to reach for his sword and fasten it on, then draw on white gloves, while Dalzell went to his quarters, next door, and did the same.

"What can be in the wind?" whispered Dan. "This is the first time that Admiral Timworth has ever expressed any desire to see us. Can it be that we bungled in some way with the Cushing business?"

"I'm not going to waste any time in guessing," replied Ensign Darrin, as they stepped briskly along, "when I'm going to have the answer presented to me so soon."

Then they halted before the entrance to the admiral's quarters, to learn if it would be agreeable for the admiral to receive them at once.

CHAPTER II

DAN'S THIRTY-THREE-DOLLAR GUESS

As the two young officers entered the admiral's quarters the curtains were closed behind them by the