5/5 A bizarre twilight network of caverns never explored by humans before is discovered.
4/5 One team looks for bats, snakes and spiders; the other sees extraordinary cave paintings.
3/5 The explorers have a close encounter with a giant python.
2/5 The humidity and parasites take their toll, as the team search for jungle elephants.
1/5 The team set up camp and search for the elusive clouded leopard and rare Borneo gibbon.