Catching Butterflies by Sandra J. Jackson

April and Beth have escaped, and their captor is dead. Freedom is in their grasp - if only they knew where they were.

With some memories returning, April and Beth struggle to find answers to their questions. What they know is that they’ve been vaccinated against a strange virus. But what happened to their family, and to the rest of the world?

As they head out, they stumble onto the compound where their nightmare began, but the empty building only brings more mystery into their lives. Soon, they encounter others wandering on the numerous trails throughout the woods. For April, finding her family is priority one; for Beth, it's sticking to the trails.

How can April ever convince her to leave the forest... and why are they being hunted?