The 100 is about 100 prisoners, five ones especially. There's been a nuclear war and a few people have escaped to the space. To protect humanity, there's been made a doctrine, the Gaia-doctrine. A few, very very VERY simpel rules of it: teen moms are not allowed...
Or Clarke. She's the daughter of two brilliant parents, doctors who do research about the effect of radiation of Earth at people who visit the Earth after three hundred years of being in space. But it's not just research. Clarke discovers something... She can't handle it alone, so she tells Wells, her boyfriend about it. And by chance, he is the son of the chancellor...
In part 1 of The 100 you discover why Bellamy -by the way, that's Clarke's best friend-, Wells, Clarke, Glass and Luke -Glass' boyfriend- are in detention, and how the other prisoners react when they're on Earth... You HAVE to read this, I swear!