In 1931, Harold Lasseter's body was found in the Central Australian desert. His diary revealed he'd discovered gold, worth millions...but that he'd give it all for a loaf of bread. The gold is still yet to be found. Lasseter's Reef is Australia's El Dorado; a fabled treasure buried in a vast and hostile environment, a magnet for fortune hunters, cranks and dreamers. Filmmaker Luke Walker finds Lasseter's 85-year-old son, still searching the desert, not for gold, but something far more precious.