According to the Netflix algorithm, I was supposed to like this a lot more than I did. I may just not have been in the mood, and if I'd hit it on a different evening, I would have been more caught up in it. But I'm not a Professional Movie Reviewer, I don't even consider these blog posts to be "reviews", and (as always) your mileage may vary.
That said: it's a Korean violence-fest, and the plot seems clichéd. (Even though I can't point to a similar one.) Cha Tae-sik is an ex-cop-of-some-sort, turned into a recluse by the death of his wife and unborn child. A cute precocious little girl, So-mi, intrudes into his self-absorption; unfortunately—and ain't it always the way—So-mi's mom is involved with drug trafficking, and decides to do a little freelancing. That doesn't work out well for mom, and So-mi is kidnapped by some very bad guys. Cha Tae-sik must (of course) rescue So-mi, and it involves getting in the midst of a Korean gang war, evading the cops, and piling up a whole bunch of bodies.
The climax, unfortunately, involves some gunplay that even I (who knows close to nothing about guns) am pretty sure wouldn't work as shown.