On the Indonesian island of Flores, archaeologists uncover a skeleton about a meter tall, buried for roughly 18,000 years and first mistaken for a child. Closer study shows an adult female with a brain no bigger than a chimpanzee's, sitting alongside stone spear points and the bones of dwarf elephants she may have hunted. The film follows the excavation team as they piece together an island ecosystem turned upside down: elephants shrunk to pony size, rats and lizards grown oversized, including the Komodo dragons that still live there. Researchers argue over what the skeleton means, whether it belongs to a genuine new human species or a modern person with a growth disorder, and the BBC Horizon crew tracks the debate through lab analysis and field interviews. A visit to a living pygmy population near the dig site adds a present-day angle to the argument, raising the question of how recently small-bodied humans might have survived on Flores. The find keeps unsettling a simple story: that modern humans were always the only kind of human left standing.