How does Nunez end up in the country of the blind?

The short answer is that he falls. More amply, the character of Nuñez in H. G. Wells’s “The Country of the Blind” is a guide for a group of mountaineers in the Andes. While guiding them, he slips and falls deep into a ravine. He is thereby cutoff from the party that he had been paid to guide. Nuñez finds himself a survivor within a society that had been cut off from society for 15 generations. Despite his efforts to regain contact, Nuñez is alone within a group that does not acknowledge the existence of the outside world. Captivated by their dilemma and despite his best efforts, he falls in love with a woman in that society, which motivates him to try to free her from its highly restrictive confines.