Thanks to NetGalley and HarperCollins, first off let me say I LOVED this book. I like the new take on the afterlife. This was a different paranormal romance, no vampires, werewolves, angels, fairies. There are immortal beings, and in a way, they are kind of like vampires. These immortal beings though live on the feelings or emotions of mortals. They can take it during events like concerts, like the band that Cole is in. Or they can take you to the Everneath where you will be right next to them for 100 years while they get the sustenance they need to last another 100 years. Now, this 100 years in the Everneath is much longer than how much time actually passes on the surface. And normally, after you've been here, you age too. But for some reason, Nikki, our main character, doesn't age after this 100 years with Cole. And she wants to go back, back to a face, a boy she knew. She went with Cole because she was sad, her mother had died, things with her social life were not at the greatest, and so she let him take the pain away. But by going back, instead of staying with Cole and doing what he wants her to do, to stay with him forever and maybe take over the Everneath, she now owes the shades, the creatures that connected them, and after a short time back, about 6 months or so, they will pull her back into the Tunnels, a horrible dark place she is told. But Nikki wants a chance to actually tell her family and friends goodbye this time. She needs to see the guy whose face she saw the whole time, Jack, at least one more time. Cole is there the whole time trying to win her back.This story was so good. I had to know what would happen. I loved the mythology in it, as well as the way those myths could be re-interpreted to fit this story. I'm so glad to see on Goodreads that there is a sequel, because I need to go on with this story. I'm not ready for it to end. And you won't be either.