This is about a virus on a plane. The direction, actors, and drama are good. However there are several (supposedly dramatic) moments that will make you burst out laughing if you happen to have ever heard about planes, or viruses.

So don't get me wrong, it's very well done, and there's enough stuff in the characters' background story for drama. But it's really so weird.

I guess the trophy goes to the cop showing a picture to a very diminished hospitalized researcher:
- "Do you recognize it ? Is it the virus that hurt you ? "
- "Yes, how could I forget ?"

And it's completely filled with moments like this. When they first find [spoiler]a corpse in the terrorist's place[/spoiler], in less than 10 minutes they have a confirmation that "yes, it's the virus that killed them". But at this moment,... what virus ? What did they compared it to ? (Could be a bad translation and they meant *a* virus ?)

As for the virus part of the story, it's shown that a lot effort has been put into making it faster, more transmissible and deadlier. And it seems that way at first, the first victim dies very quickly, probably less than an hour. A few more victims, a bit of panic ensues. But then after a while, even if it stays supposedly the main topic ([spoiler]it's the reason they can't land[/spoiler]), it's like it disappeared. For what is somewhere between 8 and 12 hours, nothing happens on this front. No new death, no people getting worse, maybe one or two more skin rashes and that's it. It's like the scenario has totally forgotten there was an actual virus.

As for duration, despite the constant reminder that "omg they won't have enough fuel to finish!", the plane actually [spoiler]goes, to its final destination (8+ hours flight), can't land so doubles back, makes a detour via Tokyo, still can't land, gets back to Seoul, still doesn't land and goes on a bit, and finally comes back to land[/spoiler]. That's more than twice what the plane was planned for.

The plane also does repeated uncontrolled acrobatics without any damage, with not a single luggage falling, despite people being repeatedly stuck to the ceiling.

And so, when the actual virus action is totally forgotten, the focus switches to a more political/diplomatic view: can or should the plane land ? Though the dilemma is interesting, and the political handling rather realistic (let's wait for it to solve itself without taking any decision one way or another so we don't have to deal with the consequences and responsibility), the situation is actually extremely simplistic.

First as for risk evaluation, a plane is probably one of the simplest thing to isolate and quarantine.

For the countries [spoiler]outright refusing landing[/spoiler], well, the moral dilemma just disappears since this has no consequences given the plane seems to have magical reserves of fuel, but in real life, it's just plain killing them.
It's also entirely simplified by the fact that the plane is, like no plane ever, entirely filled with Koreans. No tourists, no transits, no US citizens coming home.

The passengers' [spoiler]heroic decision to not land[/spoiler] doesn't actually make any sense and there is not thought through because do what instead ? Just [spoiler]crash the plane in the middle of the city ? Plunge it in the ocean ?[/spoiler]. We should have seen a company representative wanting their plane back. Also at this moment, remember that no one's medical situation has gone worse in more than 8 hours.

What could have been a real ethical dilemma, an interesting view on how these decisions happens, actually turns into just a cheap scenario trick to prolong tension artificially.

In fine, it's a bit disappointing that what is exposed as the main idea and topic is really just a pretext for ok, but generic character drama. And the cheapness and obliviousness with which it is used is so extreme that it can make you burst out laughing, totally getting you out of the story and erasing all artificially created tension. Quite uncharacteristic for a production of this level.