Many books and films revolve around marijuana and other illegal drugs. Sometimes drugs such as herion, cocaine, or marijuana are simply a tool utilized by characters for a higher purpose. However, many times screenplays and fictions are built around the effects of drugs on an individual's psyche, his/her life, or on society. Many of these are very interesting, and I would recommend reading or watching all of the following:
Reqiuem
For a Dream
Brave
New World