The reader is introduced to a small town in Italy in which a widow, her son, and her dog are introduced to the story. (Apologies for the robot dog, this is the only thing that came up for the tag "dog")
A vengeful widow (climax)
Antoine is murdered by Nicolas Rivolti at his workplace.
Antiones body is brought back to the widow's house. It is then, that she swears to avenge her sons death and kill Nicolas Rivolti.
A Widow Alone (conclusion)
The widow, disguised as a man, has trained her dog to kill the man who killed her son and arrives at his work place to take vengeance.
The widow has succeeded in her revenge, as the dog was able to kill the man who killed her son.
The widow, satisfied in her deed, can now rest peacefully, having fufilled her promise she made to her son.