I have said before that Lord John Roxton was obsessed with South America. He could not speak of that great country without admiration. Even the Professor’s cynical and sceptical smile would gradually vanish from his thin face as he listened. He would tell the history of the mighty river so rapidly explored, and yet so unknown in regard to all that lay behind its ever-changing banks.

“What is there?” he would cry, pointing to the north. “Wood and jungle. Who knows what it may shelter? And there to the south? A wilderness of dark forest, where no white man has ever been. The unknown is up against us on every side. Who will say what is possible in such a country? Why should old man Challenger not be right?” And the stubborn sneer would reappear on Professor Summerlee’s face, and he would sit, shaking his head in unsympathetic silence, smoking his pipe.

So much, for the moment, for my two white companions. But already we have enrolled certain retainers who may play no small part in what is to come. The first is a gigantic negro named Zambo, who is a black Hercules, as willing as any horse, and about as intelligent. We enlisted him at Para as he spoke English a little bit. There we also took Gomez and Manuel, two half-breeds, as active and wiry as panthers. Both of them had spent their lives in those upper waters of the Amazon which we were about to explore, that was the reason Lord John decided to engage them. One of them, Gomez, had the further advantage that he could speak excellent English. These men were willing to act as our personal servants, to cook, to row, or to make themselves useful in any way at a payment of fifteen dollars a month. Besides these, we had hired three Mojo Indians from Bolivia, who are the most skilful at fishing and boat work of all the river tribes. The chief of these we called Mojo, after his tribe, and the others are known as Jose and Fernando. So three white men, two half-breeds, one negro, and three Indians made up the personnel of the little expedition which lay waiting for its instructions at Manaos before starting on its quest.

At last the day had come and the hour. We were seated round the cane table, on which lay a sealed envelope. Written on it, in the handwriting of Professor Challenger, were the words:

“Instructions to Lord John Roxton and party. To be opened at Manaos upon July 15th, at 12 o’clock precisely.”

Lord John had placed his watch upon the table beside him.

“We have seven more minutes,” he said.

Professor Summerlee gave an acid smile as he picked up the envelope in his gaunt hand.

“What can it possibly matter whether we open it now or in seven minutes?” said he. “It is all part of the same system of quackery, for which I regret to say that the writer is notorious.”

“Oh, come, we must play the game according to rules,” said Lord John. “We are here by his good will, so it would be a bad form if we didn’t follow his instructions to the letter.”

“God knows what!” cried the Professor, bitterly. “I don’t know what is inside this envelope, but, unless it is something definite, I shall be much tempted to take the next down-river boat and catch the Bolivia at Para. After all, I have some more responsible work in the world than to follow the instructions of a lunatic. Now, Roxton, surely it is time.”

“Time it is,” said Lord John. He opened it and drew a folded sheet of paper. This he carefully opened out and flattened on the table. It was a blank sheet. He turned it over. Again it was blank. We looked at each other in a bewildered silence, which was broken by a burst of sarcastic laughter from Professor Summerlee.