In a dramatic atmosphere, the movie follows a man who euthanizing sick animals. He has gotten a news about a dog to kill it but he finds that it has good health so he decided to take it with him. By time, the former owner sees them together and begins to make a conflict to restore his dog.
"Euthanizer" is a cautionary tale about the wrong ways to impose your values on others (vigilantism) and the easy and avoidable danger in alienating potential allies.