IT was billed as one of Bear Grylls’s most audacious challenges yet. The Eton-educated television adventurer had to escape an active volcano in the Pacific by leaping across molten lava and avoiding clouds of “killer” gas. However, the episode of Born Survivor set on the Mount Kilauea volcano in Hawaii has emerged as faked in a scandal that has embroiled the television industry - and now threatens Grylls’s future TV career.