The Long Walk

In some horrible alternative America. 100 teen boys walk and walk and walk until only one remains. The flaggers, the ones who walk slower than 4 miles per hour, the ones who physically can't go on, the ones who literally go insane are shot dead. The real horror here is WHY? Why would they do this? What is the reason for doing this? You are given little snippets of info but you are never told and sometimes that works in a book but in this instance I don't think it does. There's lots of teenage sexy smut talk that some readers will find offensive. There's lots of teenage boy philosophising which some readers will find annoying.