“What more do you want?” he cried. “The fellow is a self-confessed fraud. We have only to return home and report him as the shameless fraud that he is.”

“Invisible ink!” I suggested.

“I don’t think!” said Lord Roxton, holding the paper to the light. “No, there is no use deceiving yourself. Nothing has ever been written upon this paper.”

“May I come in?” boomed a voice from the veranda.

That voice! We sprang to our feet with a gasp of astonishment as Challenger, in a straw-hat with a coloured ribbon… Challenger, with his hands in his jacket-pockets and his canvas shoes daintily pointing as he walked… appeared in the open space before us. There he stood in the golden glow with all his old Assyrian luxuriance of beard, all his native insolence of drooping eyelids and intolerant eyes.

“I fear,” said he, taking out his watch, “that I am a few minutes too late. When I gave you this envelope I must confess that I had never intended that you should open it. It had been my fixed intention to be with you before the hour. I fear that it has given my colleague, Professor Summerlee, occasion to blaspheme.”

“I should say, sir,” said Lord John, with some sternness of voice, “that your turning up is a considerable relief to us, for our mission seemed to have come to a premature end. Even now I can’t understand why you should have worked it in so an extraordinary manner.”

Instead of answering, Professor Challenger shook hands with myself and Lord John, bowed with ponderous insolence to Professor Summerlee, and sank back into a basket-chair, which creaked beneath his weight.

“Is all ready for your journey?” he asked.

“We can start tomorrow.”

“Then so you shall. You need no maps now, since you will have the advantage of my own guidance. From the very beginning I had determined that I would myself preside over your investigation. As to the small trick which I played on you, it is clear that, had I told you all my intentions, you should have travelled out with me.”

“Not, sir!” exclaimed Professor Summerlee, heartily. “So long as there was another ship upon the Atlantic.”

Challenger waved him away with his great hairy hand.

“It was better that I should direct my own movements and appear only at the exact moment when my presence was needed. That moment has now arrived. You are in safe hands. You will not now fail to reach your destination. From now I take command of this expedition, and I must ask you to complete your preparations tonight, so that we may be able to make an early start in the morning.”

Lord John Roxton has hired a large ship, the Esmeralda, which was to carry us up the river. Our expedition was at the time of the dry season, when the great river and its tributaries were more or less in a normal condition. The current of the river was a slight one. No stream could be more convenient for navigation. For three days we went up a stream which was so enormous that from its centre the two banks were shadows upon the distant skyline. On the fourth day after leaving Manaos we turned into a tributary which was little smaller than the main stream. It narrowed rapidly, however, and soon we reached an Indian village, where the Professor insisted that we should land, and that the Esmeralda should be sent back to Manaos.

He added that we were now approaching the door of the unknown country. Also he made each of us give our word of honour that we would publish or say nothing which would give any exact clue as to the whereabouts of our travels. It is for this reason that I have to be vague in my narrative, and I would warn my readers that it in no way can be taken as an actual guide to the country. Professor Challenger’s reasons for secrecy may be valid or not, but we had no choice but to adopt them, for he was prepared to abandon the whole expedition rather than modify the conditions on which he would guide us.