Once every 48 years, bamboo forests in parts of northeast India go into exuberant flower. Then, like clockwork, the flowering is invariably followed by a plague of black rats that appear to spring from nowhere to spread destruction and famine in their wake. For the first time on film, NOVA and National Geographic capture this rat population explosion in vivid detail and show how scientists are unraveling the connections between bamboo flowering and rat outbreaks. Ultimately, their research should help local people better cope with the next attack—due in 2056.