In the very first bit of this book, you learn that Jack lives with his grandparents, is best friends with Connor, and that he is kidnapped while drunk, nearly raped, and escapes through sheer luck.
It's all downhill from there.
I mean, sure, he's given a pair of magical glasses that transport him to another world, but given the choice between a world where friendly-seeming strangers can be hidden monsters, and a world where monsters are everywhere and clearly visible, which would you choose? Do you stay with the friend you've known and loved your entire life, or do you protect a couple of children who are relying on you to keep you safe? When the only decisions are bad ones, what do you do?
This is a harrowing, gut-wrenching, utterly enthralling, and not at all safe read, and I can't recommend it highly enough. Much like Kathleen Duey's Resurrection of Magic series, this is something that will delve deep inside and carve out a bleeding hole in your soul, and much like Jack, you'll keep coming back in spite of—or maybe because of—the pain.