Where is Mack's daughter?

The Shack: Where Tragedy Confronts Eternity - Wm. Paul Young, Brad Cummings, Wayne Jacobsen

Mackenzie, Mack for short, has it all, a wonderful wife and five kids. One day he packs up his three younger children for a camping trip. They make a couple stops before their destination to go sight seeing. Once they get to the camp site a young couple immediately befriends them. The couple get real close with the youngest of the children, Missy. As the older children go on tiny adventures Missy is to little for, the couple and Mack find things to entertain Missy. On the last night of their camping trip Mack's two children go canoeing while Mack packs up, and Missy alone coloring. Mack is suddenly interrupted by a loud splash and the sight of his daughter climbing out of the water and his son drowning. Mack rushes into the water to retrieve his son, and when they emerge from the water he spots the empty spot where Missy was planted coloring. Frantically Mack searches the whole camp and alerts authorities. With no trace of Missy and a little ladybug pin left where she sat, Missy was announced missing.