Summary:

Sara has led no life. Only two days after her birth, a mysterious plague wiped out the entire human population. She wasn't sure if she had been immune or not, but something kept her alive.
When Sara turned fourteen, she became aware that she was not the only survivor in that empty, shallow world. Somewhere, in a distant city, more children were fighting for their lives. But Sara isn't supposed to go anywhere.
The force that kept her alive seems more and more hostile. It wants Sara for itself. Whatever it is, it doesn't want Sara to leave...
And it if lets her go? Then those children are in for the ride of their lives, no matter how short it has been.