Existence ~ Paperback ~ Megan Hood

Over a hundred years into the future, humanity has reached the point where it would rather eliminate itself into extinction than risk becoming infected by what they think is a virus. Mutated creatures, born from the virus and human blood, roam the Earth in search of food - human food. When it seems all hope of saving the human race is lost, rumours circulate about a New Government who claim to have found a "cure." A young woman named Margot, armed with only a sword, enters the woods alone knowing she may never come out again. She almost doesn't... Three days later her captor offers Margot food and water, forcing her to promise she won't run or try to kill him. Suspicious of his sudden kindness, Margot resolves to run at the first opportunity. However, the more time she spends with him the less she wants to run. It's not until they come across an abandoned house surrounded by a huge metal wall does Margot start to suspect she's put her trust in the wrong person. A scientist's journal is found and the horrible truth behind the virus is revealed. Margot has to figure out exactly who her mysterious companion really is before it's too late.