The USSR implodes, China reforms and other countries embrace capitalism. It looks like mankind’s experiment with socialism is ending.

Despite a record marked by economic failure, political repression and countless lives lost, socialism makes a surprising comeback across the world – even in the United States, where Senator Bernie Sanders hopes to carry it into the White House.

Karl Marx said a workers' revolution was inevitable but by the end of the 19th century, it had failed to materialize. In response, some of his followers began developing an important strain of Marxist thought that would deeply affect America and the West.

Italian communist Antonio Gramsci concludes that to succeed, Marxists must overthrow not just capitalism but Western civilization. Scholars of the Frankfurt School take refuge in Los Angeles - ground zero for the American culture they hope to destroy.

In the 1960s, the 'long march through the institutions' begins: a systematic effort to control higher education and other key institutions. Herbert Marcuse emerges as 'the Godfather of the New Left,' inspiring a new generation of American socialists.

In the 1970s, socialists took aim at environmental issues. From overpopulation to global warming, they provide in every case the same prescription: more centralized control and less personal freedom.

Today's socialists substitute conflict over race, gender, and identity for the original Marxist schism between owners and workers. The goal remains the same, however: destroy American institutions, disrupt society, and bring about revolutionary change.