Filming for the movie adaptation of "The Shack" has already begun in Vancouver," Canada, with Sam Worthington ("Avatar," "Wrath of the Titans," "Clash of the Titans") taking on the role of grieving father Mackenzie "Mack" Allen Phillips, and Octavia Spencer ("The Help," "Divergent") playing God or "Papa."

"The Shack" is the New York Times best-selling novel written by William P. Young that has sold over 22 million copies worldwide. It tells the story of a father's life-changing journey after suffering from the tragic loss of his daughter. The film shows how he learns to deal with the truth about love, loss, and forgiveness.

Mack enjoys a pretty happy life with his wife and their three children, but everything changes when his youngest daughter Missy gets abducted from their vacation campsite. All of the evidence gathered by authorities pointed to Missy being murdered, but her body was never found. This causes Mack to spiral out of control and question everything he has ever held dear—including his faith in God.

But one day, Mack receives a mysterious letter, apparently from God, urging him to go back to the crime scene—an abandoned shack deep in the Oregon wilderness. Mack is doubtful, of course, but he makes it there nonetheless. On his journey in the cold mountain woods, he meets a trio of curious strangers. One of them is a woman named Papa (played by Spencer). With the help of these strangers, Mack confronts the tragic death of his daughter and finds peace and acceptance.

The cast includes Tim McGraw ("The Blind Side"), Radha Mitchell ("Olympus Has Fallen"), Alice Braga ("Queen of the South," "Elysium"), Aviv Alush ("The Gordin Cell"), and Graham Greene ("Longmire"). The film will be released by Lionsgate's Summit Entertainment label.