I think I can say with total conviction that this was probably the worst 80s revival splatter movie I have seen, well since the 80s.
What was that? And even more important, why did several really fine Korean actors take part in this? And most important: there is tons of really fantastic Korean movies that could represent the unique quality of storytelling and actors abilities to the world to be send to international film festival and of all the great stuff that is there coming from Korea they chose this movie? Why?
But let me sum up why I am saying this:

Storyline:

well, there is none really, and I mean none. A short glimpse back to 2017 where some severe criminals should have been transported back from the Philipines to Korea. And there it starts to get funny. So they plan to transport the most severe criminals fom one country to another and do what? They showcase them like on a red carpet in front of non-checked audience and one of the audience members has a bomb? Ok, totally unrealistic.

Cut, it's 2019, they make another try to transport the criminals back to Korea. And what would you do if you would plan this? I tell you what you would not do. You would not just put some little handcuffs around their wrists, leave them all together on that ship with no restrictions? If you would plan to move so many of the most dangerous cirminals you would, in the year 2019, not 1959, of course have them heavily restricted, not only with handcuffs. You would have single closed cells on that ship where every single one of them is confined for the whole trip, just a small box opening to get them food. But no, here we see how they are just let them onto the ship, they can all sit together on the ground just their hands cuffed, and waiting to get loose. How ridiculous is that?

The police staff, I really had to laugh at some point. Most of them don't have guns to start with (very unlikely again on such trip) and those who have them, esepcially Jung So min, an actress I normally adore, is probably doing the most senseless and unable things imaginable. She is a times standing around like a deer in the spotlight, awkwardly holing a gun and - not shooting it when all hell breaks loose =D

The movie has no real dialogue except for foul mouthed slang and cursing and hissing all the time, very chliche, and the movie very soon turns into the most ridiculous splatter festival. And not even that is good! They totally overdid it for the sake of being supercrass which I found totally annoying. So there is like single blows to body parts and the next moments around 200 liters of blood spread like heavy rain through the whole room=D And very soon there is nothing else anymore in that movie, just lots of unrealistic 'i want to be so crass' splatter nonsense.

I started fast forwarding at some point and all of a sudden some super human blood covered 'thing' shows up and simply kills everyone in the most gory way, I didn't even get why but I really started laughing.

conclusion:

there is at least four actors and actresses in this movie I normally really like a lot and all of them are excellent actors in other productions. What made them think to say yes to such a trashy scipts is beyond me, I really can't understand it.

I seriously hope I can see all of them in better productions in the future, where they can show the quality acting they are all able to deliver easily under other circumstances.