This is one of those movies that makes me proud to be a Korean! I kid (sorta) but I would have to straight-up hate a country to not be able to appreciate a good origin story. Whether it’s a Tea Party or Thermopylae or Exodus, people finding freedom and creating their own ideal of a country is just rousing. (Well, I’ve assiduously avoided Reds which tells you something.) Anyway, the Koreans kick ass at this sort of thing.
Forbidden Dream concerns the same king we learned about in The King’s Letters. In the Korean mythology, he’s like a blend of Isaac Newton and King Arthur. He invented their alphabet so that people could read, per that movie—but by this one, he basically unleashed Korean astronomy. Koreans, as you will recall, were under the thumb of the Chinese at the time, and this really didn’t work out when it came to astrology and farmer’s almanacs.

Star bros.
Now, much like the trilogy of movies we saw in 2018, especially Fengshui, as a modern Westerner, you kinda gotta think, “Well, wait, isn’t this all bullcrap anyway?” But it’s not really the point. That’s like arguing that Sparta was a militaristic slave-driven society that really didn’t advance the cause of freedom.
The point, really, being that the world belongs to those who can take a stand. As scary as the Persian Empire was to ancient Greeks, so too the Chinese to medieval Koreans.
Anyway, despite being another movie at the same time as The King’s Letters, it’s entirely different from that film. TKL is an ensemble picture, very light-hearted despite the intense drama (and stakes). Forbidden Dream turns out to be, of all things, a buddy picture.
The story is that the King Sejong (Suk-kyu Han) comes into possession of some Indian knowledge (much like the impact of Sanskrit in TKL) on how to make a water clock, only they need an elephant. No good, as it turns out, because the one elephant they got (as a gift), well, they let it go because it ate too much. Honestly, his men can’t even read the instructions.
But it turns out, a low level slave, Jang Yeong-sil (the great Min-sik Choi, Oldboy, I Saw The Devil, The Admiral, A Heart Blackened) can read it, and what’s more, he’s sure he can build the clock without an elephant, using only Korean stuff.
And he can.

Early Asian electronics.
So, Sejong promotes him from slave to fifth-level engineer, or some similarly low-level freed-man position. This causes tremendous strife amongst the bureaucrats who insist that the caste system is the only thing keeping chaos from destroying all. Sejong works out some sort of compromise, but he takes a huge liking to Jang and the two bond over the stars, which Jang helps the king see in a number of clever ways.
Jang is interesting, because he’s very much bonded to his slave identity. Even as he rises in the ranks, he’s still very much in that degraded mentality. Meanwhile, the advisers (who cause tremendous trouble throughout Korean history, heh) naturally scheme to find ways to alienate Jang from Sejong.
In fact, the movie opens with the Chinese demanding the Koreans destroy all the astronomy equipment (since they obviously stole it from the emperor) and King Sejong’s palanquin—a massively luxurious construct devised by Jang—collapsing, having been tampered with. And the whole movie backfills the story as to why that’s such a big deal and how it came to pass: How the slave and the king became best friends, and how they were driven apart.

Korean movie medieval science labs look very wizardy.
My inclination, as with most of these historical dramas, is to pronounce it “GREAT” but I can accept that I’m possibly just starved for good, nationalistic material. The Koreans are really good at this, though. This story is largely made up, based on a handful of meager historical data, I have no doubt. But even as he shapes the story, director Jin-Ho Hur gives us interesting things to ponder.
So, of course, the bureaucrats are wicked and self-serving, as are the Chinese, but what’s interesting is that when the king confides in Jang that he’s making an alphabet for everyone, Jang is offended. He feels very much that the current order is as it should be, and worries about disruption. The king realizes the struggle he’s facing at that point.
In the end, the action boils down to Jang’s loyalty versus his desire to survive, and it’s interesting that the loyalty is (less prominently) to Korea or its king than it is to a man he considered a friend. His north star.
Of course, the big argument these days is that nationalism is evil and leads to war and whatnot, but I disagree. It’s not only fine to be proud of your country, it’s necessary.

When your palanquin gets a flat and there’s no AAA.