Tropical cyclones form over warm ocean water and grow into some of the most destructive storm systems on the planet. This episode from the Deadly Disasters series tracks how they develop and why their winds and rain cause damage on a scale few other natural events match. Cyclone Nargis, which struck Myanmar in 2008, left a reported 12.1 billion dollars in damage, and the film revisits Cyclone Idai, one of the worst storms ever recorded to hit Africa and the Southern Hemisphere, which tore through Mozambique, Zimbabwe, and Malawi in March 2019. Eyewitnesses describe what it was like to be on the ground as these storms made landfall, while meteorologists and disaster researchers explain the atmospheric conditions that turn a tropical depression into a killer storm. The film mixes archival storm footage, damage survey images, and studio interviews to walk through cyclone formation, forecasting, and the human toll left behind once the winds die down.