The Host (2006) / Gwoemul (UK-import)
Selling his wares to passers by along Seoul's Han River, life is peaceful for a small-time snack bar owner and his dim-witted son. However, the tranquillity of their day-to-day lives is shattered when a mutant creature emerges from the depths of the Han and embarks on a blood-thirsty rampage. While many of the local citizens are scrambling to escape, the father, son and other assorted family members must seek out their newfound nemesis, in order to rescue a relative.