Percy Fawcett set out to solve a mystery and only compounded it. In 1925, after studying ancient legends, the British archaeologist became convinced that the dense Matto Grosso region of western Brazil concealed a lost city that he called “Z.” In May he set out with two other men into the uncharted jungle, leaving a note that none should try to rescue them if they did not return.

They didn’t. The decades that followed brought many rumors: Fawcett had been murdered by Indians, killed by a wild animal, stricken with amnesia or felled by illness. In all, 100 rescuers in 13 expeditions have died trying to discover what happened to him. To this day, no one knows.