A screenplay’s theme should reveal to the audience your protagonist’s inner and outer journey as they move through the story.

For example, a story about a boastful barbarian that sets out to capture a jewel could have a theme that says ‘The impossible humbles all, even the most boastful of us.’ As they move from being a flawed individual, to realising their shortcomings, to becoming a better person, theme is revealed.

How this plays out across five acts:

Act 1: The protagonist is unaware of the theme and unknowingly resists it. 
Act 2: They have experiences that help them to understand the theme, resistance lessens. 
Act 3: Through conflict, vital knowledge is revealed that enters them into the theme. 
Act 4: They must finally come to grips with what’s inside to accept their new self.
Act 5: They finally realise the truth behind the theme’s message and fully embrace it.