Welcome to the Matriarchy. Sixty years after a virus has wiped out almost all the men on the planet, things are pretty much just as you would imagine a world run by women might be: war has ended; greed is not tolerated; the ecological needs of the planet are always put first. In two generations, the female population has grieved, pulled together and moved on, and life really is pretty good - if you're a girl.
It's not so great if you're a boy, but fourteen-year-old River wouldn't know that. Until she met Mason, she thought they were extinct.