This movie wasn't at all what I was expecting. After watching too many South Korean movies about war, police, gangsters, and/or serial killers, I anticipated a bleak film laden with violence and gore. Well, there was enough of that to get the point across (a scene involving skeletons will be hard to forget) but this wasn't another story of hard-bitten professionals; rather, the heroes are a hapless and frequently ridiculous family (a scene of their hysterical grief tips over into comedy). They are desperate to save a little girl from the monster.
This is a very political movie. The very first scene, in which the Korean assistant of a scientist from the US obediently pours a ton of mutagenic chemicals into the Han River, is repeated in different ways through the movie, as Korean authorities meekly go along with brute force American tactics. Their Kafkaesque refusal to listen forces the family to go it alone with whatever meagre resources they can muster. The director, Bong Joon-ho, played down the anti-American angle in an online interview, but the movie's climax repeats that first scene of careless poisoning.
The monster is incredible. It's fast and agile. Its integration into the live footage is seamless. Its design is simultaneously like and unlike real-life animals - you don't have to browse through too many pictures of marine worms online to see some truly unpleasant and overcomplicated mouths. The scenes in which the heroic little girl tries to outsmart it are frequently heart-stopping.
This is one of those movies where, with setback after setback, you cannot fathom how the protagonists can possibly prevail. And yet, somehow, in the face of an actual monster and metaphorical monsters of bureaucratic indifference and political expediency, they muddle through on sheer determination and love.