This is the story of some animals in farm in England that have enough with the farmer, kick him off the farm and have a full revolution.
What is fascinating is that it shows that in most revolutions that the revolution really does go full circle. The pigs are the smartest animals on the farm, and while they start out carrying their load of the work, it quickly becomes obvious that their best talent is thinking for others. The concrete rules on which Animal Farm is established seem to change in order to fit the pigs, but the other animals have no choice but to accept it. They are constantly being told that no matter how bad things get, it is always better than it was when the farmer was there.
In the end the pigs completely take over the role of the old farmer and the revolution is complete.
Orwell is a dark writer and seems to illustrate what can happy to society if not kept in check. I thought this book was excellent.