Stuck in a society
Looking at the summaries of the three books, you can see that in each movie there is a group of people which is locked in a place and can't get out for a certain amount of time . For Twelve Angry Men this place is a jury room, for Lord Of The Flies it's a deserted island and for The Shawshank Redemption it's a prison. Because all these people are stuck together, they are forced to communicate with each other and have to hear each others opinions. In all three books you notice that as time passes, the situation changes. In some stories, relationships improve and in some stories huge arguments and conflicts arise. From reading the books you learn that just like in real life, some people get along better and gravitate directly toward each other and some, on the other hand, dislike each other and don't get along at all.
Thesis
How do humans react when they are obligated to communicate with each other?
Poem
While reading these books, all of them discusses how each person is different from each other and how we all have apposed opinions. Listen to the poem, written by Francis Duggan, I read on this topic in the video below.
https://youtu.be/8JWQyRh-q24
https://youtu.be/8JWQyRh-q24