The weather continued magnificent. The barometer on the chart-house wall was high and steady, the sea like a sheet of painted glass. On board the Naomi the perfect luxury, the admirable efficiency of the service might have led one to fancy oneself at Cowes but for the boundless expanse of the Pacific surrounding us. The sun-burnt faces, the natty white caps and the spotless white drill of the crew, the brass-work polished until the blaze of the fierce sun upon it made the eyes ache, the long chairs set out invitingly under the striped deck awnings—it all brought back Regatta Week to me so vividly that I sometimes imagined one had only to look over the ship's side to see the boats setting down the visitors at the Squadron steps.  
There were deck quoits, shuffleboard and various other ship's games for our amusement. But it was too hot for violent exercise. The men rigged up a huge canvas bath, contrived out of a mainsail, in the bows forward, and here, each morning before breakfast, Garth, Custrin and I used to disport ourselves like young seals in their tank at the Zoo. For the rest, the day passed very pleasantly with a little gossip, a little music, a little bridge. We three men, following a custom which Garth had established, took our trick at the wheel and when Custrin had finished his watch, Marjorie reported for duty and proved herself the best helmsman of us all.
 
As a matter of fact, I had no time to be bored. I spent many hours in the chart-house with Garth and Lawless settling the details of our contemplated expedition. There was, in truth, much to plot out and arrange. The captain was more emphatic than ever against the idea of anybody beyond us three being let into the secret of the treasure-hunt. In fact, as our discussions proceeded, he showed himself increasingly reluctant to grant us as long as a week on the island.
 
"It's asking too much, Sir Alexander," he said, shaking his red head, "to expect the crew to remain cooped up in the yacht in sight of green land and not a man allowed ashore. I might hold 'em in hand for a couple of days; but after that it will be difficult, very difficult, as well you and the major here must know!"
 
It was Garth, with his quick business mind, who made the suggestion which solved the problem. Raising his head from the chart which he had been studying while Lawless, in an aggrieved tone, was presenting his case, he said:—
 
"I've got it. You can maroon us!"
 
"Maroon you?" repeated the captain in a puzzled voice.
 
"Aye! Dump us ashore and then take the yacht to Alcedo!"
 
Alcedo, he explained to us with chart and "Sailing Directions," was an islet lying some ninety miles west of Cock Island, a small, uninhabited rock, the home of seabirds of all kinds.
 
"You can get some shooting," Sir Alexander added, "and, if the 'Sailing Directions' speak true, good fishing. There's a fair landing on the north face, it says here, and a run ashore will do the men all the good in the world. You won't have above two or three days at the most at the rock before it will be time to put about and sail back and fetch us off!"
 
Lawless raised various objections, all of which did him the greatest credit. He didn't like leaving us. Suppose something happened to the Naomi? But Garth swept all objections aside. Then Lawless played his last trump.
 
"And what about Miss Garth?" he queried. "How will she like leaving you ashore on an uninhabited island? Or do you propose to take her with you?"
 
Garth rubbed his nose rather sheepishly.
 
"H'm," he mused. Then, "Okewood," he remarked, "this will be a little difficult. How about taking Marjie ashore at Cock Island with us?"
 
But I promptly negatived this idea.
 
"Out of the question," I retorted. "We're going to rough it, Sir Alexander. And it will be no life for your daughter. Why, we aren't even taking a servant!"
 
Garth jibbed at that. It would be bad enough leaving Marjie, he grumbled, and how he would face her he didn't know. But he must have his man with him. He must have Carstairs. In that I was inclined to support him. I had taken a fancy to Carstairs. I liked his honest, sensible face; he knew Garth and his ways; besides, he seemed a knowledgeable sort of chap and I had an idea that his experience with the sappers in the war might prove uncommonly useful when we pitched our little camp. It was ultimately decided that Carstairs should accompany us.
 
Then Garth suggested that we should take Custrin as well.
 
"Capital fellow, the doctor," he remarked, "what the Americans call a good mixer. I like Custrin. And he'll be useful, you know, Okewood, in the case of snake-bite or anything like that, eh?"
 
Now, as I have explained, I hadn't particularly cottoned to Custrin. Since that first night out he had made famous progress with Marjorie and while Garth and I were sweltering in the hold, assembling equipment and supplies for our expedition, she and the doctor had sat for hours at the piano in the saloon. I have always tried to be honest with myself and I may as well admit that I was envious of Custrin's delightfully easy manner. He was never gauche or sheepish with Marjorie and I knew what a boor she had set me down in her estimation.
 
So I demurred from the proposal of Sir Alexander. The party was big enough, I urged; to add another mouth would mean seriously increasing the amount of supplies we should have to take with us.
 
"But Custrin's a first-class geologist as well," pleaded the baronet, "and his knowledge should prove most valuable in our quest!"
 
I felt a very unpleasant suspicion dawn within me. Was it possible that Garth had told Custrin about the grave on the island and the clue that lay in my letter-case?
 
"Have you told Custrin about the treasure?" I asked bluntly.
 
Garth looked decidedly uncomfortable.
 
"The doctor's a most reliable fellow and highly recommended, very highly recommended to me. You can see his references if you wish, major. He is quite one of us, you know, and I did not think there was any harm.... Really, I think he'd be a distinct asset. Besides, he'll be horribly disappointed now if we don't take him!"
 
Then, of course, I knew that Garth had told Custrin the whole story and had definitely promised him into the bargain that he should join our party. I remembered now that the two had been in the smoke-room alone together for an hour or more after lunch. I breathed a little prayer of thanksgiving that in my almost wholly Irish nature a little store, an isolated stronghold, as it were, of caution, legacy of some unknown ancestor, was included. Throughout my career in the Secret Service I have made it a practice, when disclosure is necessary, to disclose only as much as is absolutely essential to the business in hand. My brother Francis, probably the greatest secret agent our country has ever had, gave me this tip.
 
Accordingly, I had told Garth nothing of El Cojo, the man of mystery, of his appearance at Adams's hut or of the Vice-Consul's warning. Apart altogether from this cautious instinct of mine, I knew next to nothing of this romantic cut-throat, and until I did I had no intention of jeopardising my chances of sailing with Garth by alarming the owner of the Naomi. I now realised that everything I might have told Garth about El Cojo, the baronet would have inevitably passed on to the doctor.
 
As for Custrin, I had nothing whatever against him. But he was a stranger—and in our job, if we don't necessarily "'eave 'arf a brick" at the stranger, we are exceedingly cold to him. Custrin was a perfectly civil, unassuming Englishman; but in my career I have refused confidence to many a fellow-countryman far more patently trustworthy than he. His rather mixed upbringing would, for one thing, have prompted me to wariness and Garth's ready confidence in him really rather horrified me. I was quite determined not to have him on the island with me and I said so as frankly as possible. On that, with rather an ill-grace, Garth capitulated.
 
The Naomi carried a small camp equipment with two light and portable Armstrong huts in sections. There was a fold-up camp bedstead for Garth, while I had my battered old Wolseley valise and my flea-bag from France. In addition to our provisions, such as biscuits, tinned food of all kinds, groceries and a suitable stock of drinks including a case of soda-water, we added, as general stores, some electric torches, a couple of ship's lamps and a good supply of candles, a large picnic basket, some mosquito netting, a medicine chest, a couple of axes, and two spades and two picks which Lawless extracted from the stokehold. There were kitchen utensils for Carstairs, who, it appeared, was an excellent cook. Garth had a pair of shot-guns and a Winchester and the three of us had an automatic pistol apiece. This constituted our armoury. I thought of those "volcanic peaks" of which the "Sailing Directions" spoke and sighed for a box of gun-cotton, a tube of primers and some lengths of fuse such as we used to carry with the battery in France. But well-equipped as she............