Usually, attempts to milk a feature-length film out of a short story come up dry (think of all those Stephen King turkeys). Here’s an exhilarating exception, taken from Kurt Vonnegut’s brisk six-page story. It’s 2053, and America is a completely “egalitarian” society, in that everyone is “average” — everyone has been electronically dumbed-down and handicapped, so everyone is the same. Harrison Bergeron (Sean Astin), a smart high-school student who keeps getting left back because of his shameful high grades, is selected by the covert elite government to work for them or else have “corrective brain surgery.” Christopher Plummer, the man in charge, explains that after the Second American Revolution — in which the have-nots waged war on the haves — it was decided that a society without envy or diversity would be a society without strife. But it’s also a society without excellence and love. This brilliant, often upsetting satire, a Showtime original, is really no more about 2053 than Orwell’s 1984 was about the then-future 1984. Astin is a little too all-American boy scout — the character as conceived by Vonnegut calls for a rebellious young Malcolm McDowell — but he’s likable, and Plummer is great as the draconian bigwig with divided loyalties. The interesting supporting cast includes Buck Henry, John Astin, Eugene Levy (as the president!), Howie Mandel, and Andrea Martin.