Socialism promised a classless world built on collective ownership of factories, farms, and land, and for a large part of the twentieth century it commanded the loyalty of millions. Host Ben Wattenberg traces the idea back to the Enlightenment and the French Revolution, then follows it forward through the labor movements, revolutionary parties, and Cold War states that tried to build it in practice. The film brings on intellectuals, politicians, and activists who argue socialism as a path to social justice and economic equality, set against critics who saw central planning as a threat to individual liberty and, eventually, a producer of shortages and repression rather than abundance. Archival material and interviews carry the case study through the movement's peak influence and its later retreat as planned economies stagnated and one-party states lost legitimacy. Wattenberg keeps both camps on screen rather than settling the argument for the viewer, using the historical record, from nineteenth-century utopian experiments to twentieth-century state socialism, to test the gap between the promise and what actually got built.