The edge of everything / Jeff Giles.

Enhanced descriptions from Syndetics:

"A sharp fantasy thriller." -- People
"Swoonworthy." -- Time
"Sharp, dark, thoughtful and romantic." --Cassandra Clare, #1 New York Times bestselling author

When their worlds collide, X and Zoe are pushed to the edge of everything in this much-buzzed-about tour de force fantasy from Entertainment Weekly veteran Jeff Giles.

For the perfect love, what would you be willing to lose?

It's been a shattering year for seventeen-year-old Zoe, who's still reeling from her father's shocking death in a caving accident and her neighbors' mysterious disappearance from their own home. Then on a terrifying subzero, blizzardy night in Montana, she and her brother are brutally attacked in the woods--only to be rescued by a mysterious bounty hunter they call X.

X is no ordinary bounty hunter. He is from a hell called the Lowlands, sent to claim the soul of Zoe's evil attacker and others like him. X is forbidden from revealing himself to anyone other than his prey, but he casts aside the Lowlands' rules for Zoe. As they learn more about their colliding worlds, they begin to question the past, their fate, and their future. But escaping the Lowlands and the ties that bind X might mean the ultimate sacrifice for them both.

Gripping and full of heart, this epic start to a new series will bring readers right to the edge of everything.