A foreign policy reporter and her Iraq veteran husband turn their sights on the hidden impact the US military has on the planet, after the birth of their first child creates anxiety about the climate crisis. Their investigation exposes a secretive and constantly-expanding web of pollution, cover-ups and unaccountability by the world's biggest polluter. Drawing on powerful testimonies from veterans, scientists, and frontline communities, they uncover how military operations poison ecosystems, accelerate global warming, and sacrifice the future for endless expansion. From Alaska’s melting glaciers to contaminated bases across the U.S. and toxic battlefields abroad, Earth’s Greatest Enemy delivers a provocative and unflinching examination of the untouchable institution playing an outsized role in the climate crisis.