The novel, Fifty Shades of Grey, which was written online by a first-time author, the female British TV producer E L James, was at the top of the New York Times best seller list for e-book fiction on Monday, and also claimed fourth spot on Amazon.com's best-selling books for its popular Kindle e-reader.
Described in the US press as "mummy porn" or "Twilight for adults", because of its popularity among housewives and adult women readers, the book was originally published chapter-by-chapter on an online site and was picked up by Sydney company The Writer's Coffee Shop, which under the guidance of Amanda Hayward, had to work for 10 months to persuade the author there was a market for it.
Now the English-language rights have been picked up for a seven-figure sum by a division of Random House, which is releasing a new e-book version of the book and two sequels this week, and plans a print run of 750,000 copies to hit US stores in a few weeks.
With the author's agent reportedly fielding numerous offers for the film rights, the reaction to the book has been compared to the viral excitement ignited by such pop cultural icons as The Da Vinci Code, The Kite Runner and Eat, Pray, Love - despite, or perhaps because of, its focus on graphic kink, complete with chains, whips and handcuffs.
The book has also been credited with sparking a rush among New York women for buying the kind of grey ties worn by the protagonist, and for almost single-handedly reviving the jaded sex lives of married couples in the Big Apple.
The story revolves around the relationship between alluring billionaire Christian Grey and college student Anastasia Steele, who is a sexually clueless virgin when they meet.
The two develop a dominant-submissive relationship filled with kinky sex acts. While critics have blasted the author for her "plodding prose" readers appear willing to overlook the literary shortcomings in favour of the bodice-ripping descriptions.
The book has sparked a media craze on US websites, TV shows and newspapers, with everyone from CNN to the New York Post to the Today show discussing the steamy publishing phenomenon.
"I found myself explaining what BDSM (bondage, discipline, sadism, masochism) was to some of the mums at Saturday morning basketball," publicist Alison Brod told the New York Post.
"The books are really making people want to have sex again. They're a Band-Aid for marriages that maybe weren't falling apart, but were getting stale," said Lyss Stern of Divamoms.com, an early admirer of the novel.
The success of the book has also been attributed to the rise in the number of e-readers and iPads, which are allowing women to read the steamy tome without letting on to anyone that the object of their fascination is what can only be categorised as soft-porn.
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