1984 by George Orwell.

I read this in my teens, but decided to have another go at it, and it impacted on me in a much stronger way this time. This is written in the then future and Britain has become part of a larger continent called Oceania. The population are basically a lot of brainwashed zombies but the hero, Winston, begins to fight against Big Brother. Unfortunately, he is ultimately crushed.

The country portrayed displays some startling and worrying similarities to modern day Britain and is a wake up call for those of us who believe everything they are told.