There's No Place Like Here by Cecelia Ahern

Sometimes it takes losing everything to truly find yourself...

Since Sandy Shortt's childhood classmate disappeared twenty years ago, Sandy has been obsessed with missing things. Finding what is lost becomes her single-minded goal--from the lone sock that vanishes in the washing machine to the car keys she misplaced. It's no surprise, then, that Sandy's life's work becomes finding people who have vanished from their loved ones. Sandy's family is baffled and concerned by her increasing preoccupation. Her parents can't understand her compulsion, and she pushes them away further by losing herself in the work of tracking down these missing people. She gives up her life in order to offer a flicker of hope to devastated families...and escape the disappointments of her own.

Jack Ruttle is one of those devastated people. It's been a year since his brother Donal vanished into thin air, and he has enlisted Sandy Shortt to find him. But before she is able to offer Jack the information he so desperately needs, Sandy goes missing too...and Jack now finds himself searching for his brother and the one woman who understood his pain.

One minute Sandy is jogging through the park, the next, she can't figure out where she is. The path is obscured. Nothing is familiar. A clearing up ahead reveals a camp site, and it's there that Sandy discovers the impossible: she has inadvertently stumbled upon the place-- and people--she's been looking for all her life, a land where all the missing people go. A world away from her loved ones and the home she ran from for so long, Sandy soon resorts to her old habit again, searching. Though this time, she is desperately trying to find her way home...