Lawrence Wright's new book, "Going Clear," is a sweeping look at the Church of Scientology -- from celebrity members such as actor Tom Cruise to the legions of unknown, uniformed worker bees behind the scenes.
The book traces the faith from its founding by science fiction writer L. Ron Hubbard to its current leader, David Miscavige.
Cruise has spoken highly of Miscavige, saying of him: "I have never met a more competent, a more intelligent, a more tolerant, a more compassionate being."
But the book includes allegations by some former high-ranking church officials of a darker side to Miscavige, including accusations that he slapped or punched members of his senior staff.
Debbie Cook once ran the church's Mecca, the so-called Flag Base in Clearwater, Fla.
As part of a now-settled court battle with the church, she testified that she saw Miscavige punch a fellow Scientology executive, and that, while he never hit her, he ordered his secretary to do so.
"And she did it very hard, yes," Cook said, in an interview that aired on "Good Morning America" in February 2012. Asked why Miscavige ordered his secretary to hit her, Cook replied: "Because, you know, he was displeased about how I was answering a question. It wasn't what he wanted to hear, in some way."
The church has said claims that Miscavige punched or slapped anyone are lies, and dismisses Cook as a "defrocked apostate" who is defaming the church A church spokesman provided ABC News with a statement by the senior official Cook says she saw punched by Miscavige denying that any such incident took place.
The spokesman also dismissed as lies claims by another former Scientologist, Miscavige's own niece, Jenna Miscavige Hill.
Hill told ABC News that more than two decades ago she and other children of Scientology's elite Sea Org staff were routinely given grueling physical tasks ranging from weeding, to planting, to hauling rocks for walls.
"We would make rock chains. You'd pass the rock to the next person. They would pass it up. Then it would go in the wheelbarrow," Hill said.
She said she was 6 years old at the time. In a statement to ABC News, Church spokesman Karen Pouw dismissed Hill's account as " ridiculous and false," saying the Church school provided "an idyllic environment for children."
This week, in what may have been an attempt to blunt the impact of the new book, the church paid for so-called sponsored content on the website of The Atlantic Monthly, a well-respected magazine.
The magazine later removed the ad after being criticized that it looked like one of its actual articles.
In a statement to ABC News, the Church attacked Lawrence Wright's book as "a work of fiction" filled with "stale allegations and ever-changing bizarre tales invented by a handful of confessed liars."
Click HERE to read the full statement from the Church of Scientology in response to Lawrence Wright's book.
Click HERE to read the full statement from Knopf Doubleday Publishing Group, the publisher of "Going Clear," responding to the Scientology statement.