The Nothing is now one of my favorite urban fantasy books. It leans more toward fantasy because a lot of the story takes place in worlds that are not our own. If you like a lot of danger, some romance, and well-built fantasy worlds, I recommend reading The Between series by Kerry Schafer. It is definitely a series I would read again and again.
— Books that Hook

The Nothing

Book Three of the Between Trilogy (2nd edition)

“Everything leads up to an edge of your seat finale that blew me away. What a great ending to a wonderful and emotional series. This series is a keeper for sure!—Goodreads Reviewer

Vivian has one last chance to save the worlds, if she’s willing to pay the price... 

There’s no rest for the weary. With the Black Gates irrevocably sealed, Vivian and Zee search for another way into The Forever in a desperate attempt to stop Aidan from her plan of ultimate destruction. But the dreamworlds are dying, the Between is growing increasingly unstable, and it’s clear they’re going to need some help.
In Wakeworld, doctors and world leaders are scrambling to determine the source of a mysterious illness that is killing healthy people in their sleep. Weston Jennings knows the truth: dreamworlds are dying and taking dreamers with them. When fate unites him with an orphaned child who has latent dreamshifting ability, he takes her through into the Between in the hope that Vivian can save her – and all of Wakeworld -- from what the child calls the Nothing. 

Vivian and Zee have entered the world of the treacherous Sorcieri, who alone hold the secret of an alternate path into the Forever. But even if the Sorcieri can be persuaded to share the secret knowledge, or trusted to uphold their end of a bargain, saving the worlds can come only at the cost of unimaginable sacrifice.

Schafer proves densely plotted and emotionally charged storytelling is definitely her forte
— RT Book Reviews