Does the main character learn a lesson? If so, what is the lesson? The lesson would be the theme. If not, does an event occur that change the characters?
This event could help develop the theme. Stories have many themes. Some themes the author did not intend to have. To determine theme, pay close attention to the storyline and characters actions. If they learn a lesson, that could be a theme.
Because he was exiled by his country and anyone was a liberty to take his life if he returned. Anyone who was caught helping him was going to face consequences.
