“There’s no money in it! Just experience and expenses.”

“All right! What are we waiting for?” Johnny led the way up the gang-plank.

All that had been two months before and what wonderful months those had been! Sailing from island to island, they had taken pictures of quaint, native homes, of native women with flashing eyes, of ancient buccaneer cannon, fast rusting to nothingness. There had been three exciting fights, with men who had thought they were intruding. In one of these, a machete had come within a fraction of an inch of Johnny’s ear. He seemed to feel the cool swish of it now.

Then, he thought with a sigh, those golden days had ended. Lee Martin, the photographer, had been called back to New York.

“You keep the stuff,” Lee had said to Johnny. “You may be able to get some unusual pictures. If you do—send ’em home to me. I’ll see what I can make out of ’em, for you.”

Johnny had watched Lee’s boat fade into the distance. Then, with heavy heart, he had marched back to his lodgings in Port au Prince, the capital of the Island Republic of Haiti.

That very day he had noticed the Sea Nymph, located the man in charge, and signed up as watch. His photographic equipment was in his stateroom. He had laid in a good supply of film packs and plates. Would he find opportunity to use them? Would he get some unusual pictures to send to Lee Martin? Time was to answer all these questions in its own way....

“It’s a strange layout,” he thought, as he took a turn about the deck. “I suppose I’ll know what it’s all about before long.”

It was indeed a strangely equipped craft. A three-master, with an auxiliary motor for bad weather, the Sea Nymph had been built for island trade. Since the bottom had dropped out of the sugar market, she had been lying idle in the harbor. Without making many changes, the elderly professor had equipped her for his purpose, whatever that might be. Johnny had not yet been told. There had been a hold at the boat’s center, for sugar and other freight. This had been transformed into a tank—or swimming pool. Johnny could not tell which. Doris, garbed in a gay swim suit, had taken a morning plunge there, but he had a notion it was for some other purpose, also.

Strangest of all, close to the stern where it could be reached by the stout hoists, was a large, hollow steel ball. It was all of eight feet in diameter, and its walls were several inches thick. What, he had asked himself more than once, could that be for? But he had asked no one else. The natives would not know, and one simply did not ask such questions of an employer. Besides, Johnny had learned long before, it is a waste of time to ask questions which, in good time, will answer themselves....