Save the Green Planet (2003)

The film's main character is Byeong-gu, a man who believes that aliens are about to attack Earth and that he is the only one who can prevent them. With his childlike circus-performer girlfriend, he kidnaps a powerful executive whom he believes to be a top ranking extraterrestrial who can contact the prince of these aliens during the upcoming eclipse. After imprisoning the man in his basement workshop, he proceeds to torture the executive and slowly Byeong-gu's true intentions are revealed. It seems that the executives company poisoned his mother in a pharmacy test, and though Byeong-gu does seem to believe that the executive is an alien, he's deluding himself to his obvious act of revenge. When a detective comes calling to investigate the disappearance, the executive tries to escape but is thwarted by the psychotic Byeong-gu. The detective at first finds nothing unusual but on his way out sees Byeong-gu's dog (appropriately named Earth) gnawing on the bones of his masters past victims. After contacting a partner in the police force he is killed by the psycho's bees, is hacked up and fed to the dog. Byeong-gu then crucifies the executive and breaks his leg with his axe butt, to punish him for his attempted escape. In a desperate move, the executive convinces Byeong-gu that the bottle of benzene in his trunk is the antidote for his comatose mother.