Is the book The Shack a true story about Mack Mackenzie and Missy? Was Missy a real girl?

William Paul Young's novel The Shack is a work of fiction. The author calls it "true" fiction, and compares it to a parable. The characters in the novel are fictional, but some elements of the book are autobiographical. Mackenzie Allen Phillips bears some similarities to the author, and Missy bears some similarities to people in the author's life, but the details are fictionalized. 

William Paul Young was a missionary's son and grew up among the...

William Paul Young's novel The Shack is a work of fiction. The author calls it "true" fiction, and compares it to a parable. The characters in the novel are fictional, but some elements of the book are autobiographical. Mackenzie Allen Phillips bears some similarities to the author, and Missy bears some similarities to people in the author's life, but the details are fictionalized. 

William Paul Young was a missionary's son and grew up among the Dani tribe of Papua New Guinea. His parents were both missionaries there and were very busy with the work they were doing. Paul describes his experience there as being raised by the members of the Dani tribe, spending time with them from early morning until dark every day. He overheard them plotting to kill his parents. He was sexually abused by members of the tribe. 

Paul describes The Shack as a metaphor for the pain we all carry inside us. He talks about his own personal shack taking 38 years to construct. He talks about a time in his life in which he had lost his eighteen-year-old brother, his five-year-old niece, and his mother-in-law in a six-month period of time. His wife encouraged him to write a book for his children, and that is the audience that was originally intended for The Shack. It was then self-published, and through word of mouth became a bestseller on the New York Times bestseller list. 

Paul Young framed the telling of this story with a fictional narrator called Willie, who speaks directly to readers in the Foreword and After Words sections of the novel. This literary device lends a realism to the story that makes it seem more like nonfiction. The fictional Willie says something in the Foreword that aptly describes the experience of reading this novel:

"What you are about to read is something that Mack and I have struggled with for many months to put into words. It's a little....well, no it's a lot on the fantastic side, Whether some parts of it are actually true or not, I won't be the judge. Suffice it to say that while some things may not be scientifically proveable, they can still be true nonetheless." 

Willie raises the question in the After Words section, "Do I think it's true? He then answers that question by saying, "I want all of it to be true."