Trilogies like '50 Shades of Grey,' 'Hunger Games' are hot

Trilogies like '50 Shades of Grey,' 'Hunger Games' are hot

The evidence sits atop USA TODAY's Best-Selling Books list: The top three spots belong to E.L. James' erotic FiftyShades of Grey trilogy, followed by Suzanne Collins' The Hunger Games young-adult trilogy. Amanda Hocking became a publishing sensation thanks to her Trylle trilogy â€"Switched, Torn, Ascend.

What makes trilogies work?

• MORE: Questions for author Hilary Mantel

• MORE: Questions for author Amanda Hocki ng

• MORE: Questions for author Erin Morgenstern

"Readers come to know the subjects and characters so well, they become invested in them," says Knopf's Paul Bogaards, who is handling publicity for James and worked on another three-book wonder: Stieg Larsson's Millennium trilogy. But Bogaards also questions whether the number matters: "I don't think readers hunger for trilogies as much as they hunger for storytelling that they find deeply immersive and satisfying."

Erin Morgenstern, author of the best-selling novel The Night Circus, witnessed that on her 20-city book tour last year. A constant question: Was she writing a sequel? But "a few times I was asked if it was the first of a trilogy, and I was a bit surprised by the specificity of that," she says.

There won't be a sequel to The Night Circus, "though I sometimes feel that statement should come with an apology. … I like it as a single volume. It feels complete to me, and I wouldn't want to stretch it out into something it's not." But she was flattered by her fans' eagerness for more: "It's a wonderful feeling."

Hilary Mantel says she intended to write one novel about Henry VIII"s henchman Thomas Cromwell. But to the delight of fans and critics, the project has turned into a trilogy. It began with her 2009 Booker winner, Wolf Hall, and continued with Bring Up the Bodies, which landed at No. 19 on the list May 17.

"You could say I felt my way toward the decision," Mantel says. "I felt as if I were waking in the dark initially, and then in a flash, I saw the shape of the story."

Of course, some phenomenally successful series extend beyond three books, including the Twilight series (four volumes) and Harry Potter (seven).

British blogger Stephanie Butland (bahtocancer.com) says the trilogy is the perfect format: not too short but not too long. "You can really understand the characters and the story in three books," she says. And you don't have to panic as you reach "the last 50 pages of a really great book, because you know there's more."