I didn't get help so just re-posting.

Question

I have to write a review of a film or play I've seen and I chose the movie "Law Abiding Citizen"

I need help (the theme isn't really a theme, its the plot but I can't really come up with a theme.) Could this be it?

A man seeks revenge on the justice system for not putting the men who murdered his family in prison.

"Law Abiding Citizen"

Directed by F.Gary Gray

Starring: Jamie Foxx and Gerard Butler

Theme: A brilliant man orchestrates a series of high-profile murders that grip the city of Philadelphia - all from inside his jail cell. The prosecutor assigned to his case realizes he is the only one who can end the reign of terror.

Answer 1

http://www.tnellen.com/cybereng/lit_terms/theme.html
Notice that a theme is NOT the main idea or plot of a story. It's the author's message to his readers.

So ... what do YOU THINK the author's hidden message is in this story?

Answer 2

There are very many reviews of that movie here:
http://www.imdb.com/title/tt1197624/usercomments
Most reviews are highly favorable.
Reading how other people reacted to the movie may help you formulate your own review