Along the way it brings up several core ideas.
1. The 1 Percent will win and this will lead to eventual slavery/prostitution/the loss of basic human rights.
2. Nobody will be forced at gunpoint into becoming slaves/prostitutes/giving up their rights. They will do so willingly given the list of possible alternatives.
3. Some will be very happy to make those choices. (Though some will not.)
4. Society is moving towards a point where the only people with freedom will be criminals.
5. Consent is not as black and white as people make it out to be and, in fact, some people like to believe their consent is being violated, because it allows them be/act in ways that they would be unable to if they had the ability to give affirmative consent. I.e. believing you are being coerced is a great way to justify doing what you actually want to do.
6. You believe what you want to believe. (Sorry, Tom Petty, I just couldn't find a better phrase for the point she's getting at.)
7. Love is a drug. Since we already believe that you can't give informed consent when you are on drugs or alcohol that make you behave irrationally, how can you possibly give informed consent when in love, since love also clouds your judgement and makes it impossible to make rational decisions. Is sex when you are in love rape, because it takes away your ability to give rational consent?
The set up is fairly simple. The libertarians have won the political ballgame. This very quickly leads to a point of roughly 50 percent unemployment, massive evictions from homes and apartments, only rich people having police protection and general awfulness. In this society not only do a ton of people live in their cars, the ones who do so are considered middle class, because at least a car provides you with a roof. (In fact most of the time spent by the middle class is spent protecting their cars from people who don't have cars to live in.)
A company comes up with what seems like a very attractive solution. They have a long term private prison contract with the government. They get paid per living person locked up in their prison. But, because there are essentially no cops anymore, nobody is being sent to prison. So they buy up all the foreclosed homes near the prison, renovate them and then make people an offer. "Come to our community! We'll give you a nice home and food and booze! You just have to spend every other month as an inmate in the prison so we can keep our numbers up. Also, once you move into our community, you can't move out. But, why would you want to? It's all dirty homeless people outside our gates!"
The story follows one couple who take the company up on this offer. In what is a very smart move on Atwood's part, the members of this couple are not particularly nice people. (If they were, this would seem like a fairy tale.) But, they are not evil people either. They are simply flawed and human.
Now, what could possibly go wrong in a completely closed community centered around a prison and run by wealthy and greedy libertarians who have followed all of Ayn Rand's teachings?
Pretty much everything will go to shit, and, as the title says, the heart will go last.