Physicist David Keith, a leading and controversial figure in solar geoengineering, seeks to test his planetary-cooling technology after decades of research and theorization. His journey unfolds amid fierce debates over the ethical, political, and environmental implications of reflecting sunlight to slow global warming. Activists warn that the technology could delay fossil fuel reductions or be misused geopolitically. The documentary offers a gripping, real-time look at science shaped by public discourse, ethics, and institutional power.