This book picks up not too long after the second book left off. I get the feeling it might be only a few months later. The post-apocolyptic world is still plagued with deadly mists that dissolve almost everything in their path.
At first, it appears that Emma has found some stability, but this changes quickly. She has to make some tough decisions, yet again. This time, however, her choices require her to give up everything she loves (but not at the same time).