The Huautla Caves system in Mexico has long been the Holy Grail of cavers. Fighting floods, cave-ins and Mazatec Indians who believe the caves are holy, caving teams have competed every year to be the first to prove the cave's depth. No-one has gone further than Bill Stone, the world's foremost caver, whose 20-year obsession nearly ended in disaster. He first explored Huautla in 1976 during the frontier days of caving. Over the next 15 years he stayed at the top, inventing clothing and equipment to help in his obsession. Finally, in 1994, after years of preparation, Stone and his 44-member team entered the Sotano de San Augustin sinkhole at Huautla. It was the beginning of a journey that would untimately claim the life of one diver and force every member of the team back - except Bill Stone and team member Barbara am Ende, who forged on alone, with no hope of rescue, to set the record for the deepest cave dive in the Western Hemisphere.