Four years prior to the main events of the story, Mack takes three of his children on a camping trip to Wallowa Lake near Joseph, Oregon, stopping at Multnomah Falls on the way.

Mack is able to save his son by rushing into the water and freeing him from the canoe's webbing but unintentionally leaves his youngest daughter Missy alone at their campsite.

He enters the shack and encounters manifestations of the three persons of the Trinity: God the Father takes the form of an African American woman who calls herself Elousia and Papa; God the Son, Jesus, is a Middle Eastern carpenter; and the Holy Spirit physically manifests as an Asian woman named Sarayu.

The bulk of the book narrates Mack's conversations with Papa, Jesus, and Sarayu as he comes to terms with Missy's death and his relationship with the three of them.

Mack walks across a lake with Jesus, sees an image of his (earthly) father in Heaven with Sarayu, and has a conversation with Sophia, the personification of God's wisdom.

At the end of his visit, Mack goes on a hike with Papa, now appearing as an older Native American male, who shows him where Missy's body was left in a cave.

In 2006, Young worked with Wayne Jacobsen, Brad Cummings (both former pastors from Los Angeles) and Bobby Downes (filmmaker) to bring the book to publication after a period of sixteen months and four rewrites.

[3] Its success was the result of a "word-of-mouth, church-to-church, blog-to-blog campaign" by Young, Jacobsen and Cummings in churches and Christian-themed radio, websites, and blogs.

[11] In June 2009 a German translation with the title Die Hütte – ein Wochenende mit Gott (The Hut – a Weekend with God) was released.

However, former Mars Hill Church pastor Mark Driscoll criticized The Shack, saying that "it misrepresents God"[13] and called William P. Young "a heretic".

[16] Apologists author Norman Geisler and William C. Roach published a critique in 2012 detailing their 14 points of theological disagreement with the book (including "unorthodox", "false", "classic heresy", "non-rational", "psychologically helpful ... doctrinally harmful", and "very dangerous").

[17] Pastor Sean Cole of the Emmanuel Baptist Church in Sterling, Colorado, offered yet another critique appearing in Pulpit and Pen.

[25][26] A film adaptation of The Shack, directed by Stuart Hazeldine and starring Sam Worthington, Octavia Spencer, and Tim McGraw, was released on March 3, 2017, to negative critical reviews.

[citation needed] It is also cited in the introduction to Richard Rohr and Mike Morrell's The Divine Dance for encouraging people thinking about the Trinity again.