"I don't know what it is.

I sometimes think I am going mad." And soon after that the change was made.
An advance column, commanded by Meredith and Durnovo, was selected to push on to the Plateau, while Oscard and Joseph followed more leisurely with the baggage and the slower travellers.
One of the strangest journeys in the vast unwritten history of commercial advance was that made by the five men from the camp of the main expedition across the lower slopes of a mountain range--unmarked on any map, unnamed by any geographer--to the mysterious Simiacine Plateau.
It almost seemed as if the wild, bloodshot eyes of their guide could pierce the density of the forest where Nature had held unchecked, untrimmed sway for countless generations.

Victor Durnovo noted a thousand indications unseen by his four companions.

The journey no longer partook of the nature of a carefully calculated progress across a country untrodden by a white man's foot; it was a wild rush in a straight line through unbroken forest fastness, guided by an instinct that was stronger than knowledge.

And the only Englishman in the party--Jack Meredith--had to choose between madness and rest.