There is something else about the male peak that has unsettled observers for centuries: it catches fire. Spontaneous flames have been reported bursting from the summit repeatedly, a phenomenon witnessed by Charles Hose, the British naturalist and colonial administrator who served under the Brooke regime in Sarawak in the late 19th and early 20th centuries. Hose, a man who cataloged birds and mammals with rigorous scientific attention, offered a practical explanation. He reasoned that the bleached limestone surface of the peak acted as a magnifying glass, concentrating sunlight onto dry grass until it ignited. Whether or not his theory fully explains what the Kelabit have long observed, the fires are real. They lend the mountain an otherworldly quality, as though the ancient battle with Batu Apoi never entirely ended -- as though the mountain still carries a spark of the fire it once defeated.

In 1945, those same pale towers saved lives. Japan had invaded and occupied British Borneo in 1941, and the Allied response was to send commandos behind enemy lines to train indigenous communities to resist. The mission belonged to Z Special Unit, and one of the men selected to parachute in was Tom Harrisson -- British scientist, journalist, founder of Mass Observation, and at that point a second lieutenant in the British Army. The maps of interior Borneo were almost useless. From the RAAF Consolidated Liberator aircraft that carried Harrisson and seven other Z Force operatives, Squadron Leader Graham Pockley and his crew would have seen nothing but an unbroken green blanket of tropical forest stretching to every horizon. But Batu Lawi's sandstone peaks stood out like a lighthouse. The twin pillars told the crew exactly where they were, ensuring the commandos would land near the settlement of Bario and the Kelabit people they needed to reach. The jump succeeded. The plane did not survive the return.

Squadron Leader Graham Pockley, who had led the mission and piloted the Liberator, was shot down on the return flight to the airbase at Morotai in the Dutch East Indies. No trace of the aircraft was ever found. Harrisson, safe on the ground among the Kelabit, carried the weight of that loss. In 1946, he made the first successful ascent of the female peak, climbing with Lejau Unad Doolinih and five other Kelabit companions. Near the summit, he tucked an inscribed wooden board into a niche in the rock -- a memorial to the crew that had delivered him to safety and then vanished. The board remained there for four decades, weathering in the mountain air, until 1986, when British and Australian soldiers from the 14th/20th King's Hussars, led by Jonny Beardsall, made the first successful ascent of the taller male peak and replaced Harrisson's wooden memorial with a bronze plaque. On 14 August 2007, a team of Malaysian climbers completed another successful ascent, adding another chapter to the mountain's climbing history.

Below the exposed sandstone of the female peak, the mountain descends through distinct bands of vegetation that change with altitude. Immediately beneath the summit, mossy elfin forest clings to the rock, every branch and surface furred with dripping moss, the trees stunted and twisted by wind and altitude into shapes that look more sculpted than grown. Below the elfin zone, oak-laurel forest takes over, its canopy denser and its floor darker. These forests harbor species found nowhere else on the planet -- Bornean endemics that have evolved in isolation on the island's highest peaks. The mountain was originally proposed as part of the 164,500-hectare Pulong Tau National Park in 1984, but when the park was finally gazetted, Batu Lawi fell outside its reduced boundaries. The mountain remains sacred to the Kelabit and the Penan people who live in its shadow, a place where mythology, natural history, and wartime sacrifice are layered onto the same stone. Pilgrims still walk the two-day forest trail. They still fall silent when the peaks come into view.