Basically the movie takes place in 2016 where gas is $35 a gallon and there's another great depression. Only rich people drive so all of the highways have been overgrown or torn down, and only private jets fly, there is no commercial air travel. The only mode of transportation left is rail travel. This rail company needs to improve their lines so they want to use this new cheaper, better engineered steel, but the government is oppressive and owned by big business so they start passing laws to stop this from happening (even though a contract with conventional steel by the rail company has failed to be fulfilled for over 13 months). The steel company, Rearden steel, owns all of the necessary companies to construct its steel (ore mines, etc.) so the government passes a law that bans any man from owning more than one company (therefore Rearden must sell off his other companies to the people around him, many of whom appear corrupt and some are even working for the government to aid in his downfall).
The state science institute then falsely claims that Rearden steel is dangerous and untested and this causes everyone to shy away from the rail company trying to use it (i.e. the engineers union declares that it is unsafe for anyone to drive trains on this new line).
While all this is going on, all the great minds in America start disappearing, leaving behind the only clue, the phrase 'Who is John Galt?'. Basically you find out they're all disappearing to Atlantis because with a government that only caters to business and money there can be no progress, so all of the progress moves to Atlantis to leave America to suffer.
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That might not be the best overview of the story, but hey I tried... LOL There's a lot going on in the movie, so it's hard to give a really good explanation, and I haven't read the book so I don't have the full picture anyway.
There are going to be 3 movies, however pt 1 was a box office disaster, according to Wikipedia it debuted in 14th place and made something sad like $5 million, losing a ton of money. Luckily part 2 is still supposed to come out this Fall.
I'm excited to read the book now and can't wait for part 2. I don't know why this movie didn't do better, it was actually pretty good. The atmosphere feels great, the characters are interesting and mysterious and the music throughout the movie is amazing. Definitely recommend it.