Wayward is a… I guess I’d call it a mystery SF thriller… the second of a trilogy written by Blake Crouch and published in 2012 by Thomas & Mercer.
If you follow reviews on this site regularly, and this one seems familiar, that’s because I’ve already posted a TV review of Wayward Pines Season 1 which is based on Blake Crouch’s trilogy of books and covers a similar set of events as the trilogy of books. And I recently posted a review of Pines, the first book in the trilogy. The first book relied a lot on big mysteries for a lot of its appeal and revealed many of those mysteries at the end. I can’t talk about book 2 without talking about those mysteries, so if you want to be surprised go read the first book.