A flawlessly executed drama thriller. Director Lee Chang Dong has crafted an intelligent story that during the first half may seem to be a set-up for a melodramatic love triangle (a well written and subtle one nonetheless), yet seamlessly takes a more sinister turn in the second half, with the deeper themes of today's youth and class dynamics always present on the background.
All the 3 main performances are excellent and very nuanced in giving you as little or as much information about the characters as needed (specially Steve Yeun whose enigmatic character Ben is a joy in trying to decipher). The dialogue is purposeful and layered. The cinematography is breathtaking, particularly in it's use of the environment and during long impressive takes (one involving Jun Jong-seo's character Hae Mi during the sunset is just jaw-dropping).
It's deliberately slow, but the payoff is definitely worth it. Easily my favorite foreign movie of 2018.