Some might call/have called this a Cloverfield knockoff, except.....The Host came out first.
We have a quick back story of an American Medical Examiner/Mortician illegally dumping chemicals during the end of the Korean conflict. The chemicals eventually mutate something that will later become Gwoemul (The Host).
Present day we have a seemingly useless single father who works in the family owned convenience store located on a beach off of the Han River. To an outsider it may appear that he and his daughter have reversed roles as she appears to be much more mature then her father. This apparent role reversal isn't lost on the grandfather as he tries to whip his son into shape as he is to inherit the family business. The aloof father has an Olympic class archer sister and political activist/rebel brother who have no interest in taking over the family business.
During a typical day of being berated by his father for slacking on the job our aloof father makes some deliveries on the beach when there is an attack by a mysterious "monster". During the attack our father is connects with his daughter who has returned home from school. While they are trying to run for safety he loses his grip on his daughters hand and she is subsequently snatched away by the monster.
The rest of the movie deals with the family attempting to overcome its dysfunction and to work together to attempt to rescue its youngest member. There is a lot of drama during this part of the movie dispersed with action and even horror. Much more drama than I expected, but very necessary to properly tell this story. Kudos to the director for staying the course and telling this story in the way that it needed to be told.
Final thoughts: This turned out to be a very good movie. Not the ending I expected, but one that I found pleasing.