The Shack by Wm Paul Young mass market paperback
"Mack" Philips took his three children on a family camping trip while his wife visited her sister. Just as they were about to leave the campsite, the two older kids decided to take a last canoe ride before heading home. As their canoe overturned, and Mack went to help them, his back was turned and the unspeakable happened. Mack's youngest daughter, Missy, was abducted by a known child predator. After a massive search, evidence of Missy showed up at an abandoned cabin. Although they never found her body, everyone knew the worst had happened. For the next four years "a great sadness" fell over Mack and his family, until a note from God showed up in his mailbox. What happens next will move you to a greater understanding of God's unfailing love for us all.