Oh, to be a fly on the wall or a mouse in the corner when Alison McGhee and Kate DiCamillo get together. You just know that DiCamillo will be laughing that exuberant Ha! Ha! Ha! laugh of hers, and McGhee will be saying understated and dry things and then, after a moment, laughing too, and you know that you will be joining in, the mouse in the corner, belly-laughing away.

This is pretty much how it went the first time they met, and this is pretty much how it has gone ever since, including throughout their collaboration on a new sort-of-a-picture-book, sort-of-a-chapter-book, "Bink and Gollie," which comes out Sept. 14 from Candlewick Press.

DiCamillo, the Newbery Award-winning author of "Because of Winn-Dixie" and "The Tale of Despereaux," and McGhee, a New York Times best-selling author of books for adults and kids, both live in Minneapolis. They met in 2001, when McGhee's sister, Holly -- literary agent to both writers -- got them together.

"We all went out to dinner, and Kate and I were laughing within probably five minutes," McGhee said. "And you can probably tell we kept on, from the book."

'Bink and Gollie" comprises three short tales about two girls -- the short and irrepressible Bink, and the tall, dignified and doubt-filled Gollie. They are devoted friends, but their differences cause friction.

DiCamillo and McGhee started working on the stories in 2006, when both writers were between projects and casting about for something to do.

"I suggested that we write a book together, just for the fun and challenge of it," McGhee said. "We're both really lone wolves as writers, and neither of us had ever done anything like that. We got together at my house, I gave Kate her requisite mug of coffee, and we sat down. Neither of us had any idea how to start, and we sat there in silence for about 10 seconds, and then Kate jumped up and said, 'Well, that was fun!' and started heading out the door.

"And I said, 'Not so fast!'"

(This is pretty much the way that Bink and Gollie would have handled the same situation.)

To keep DiCamillo in her chair, McGhee came up with a story prompt -- a sock. "Alison usually works well coming up with an object," DiCamillo said. "She'll say, 'Here's my character,' and then she'll say to the character, 'What's that in your hand?' So we started with a sock. Maybe it seemed funny, a sock."

The story that came out of it was funny indeed, when Bink and Gollie, rollerskating through town, happen upon a store that is having a sale on outrageously multicolored socks. ("It's a sock bonanza!" says Bink.)

Bink is delighted with the wild socks; Gollie is appalled ("The brightness of those socks pains me"), and a rift develops.

"Immediately, they took on aspects of our own personalities," McGhee said. "I don't think anyone who knows either of us could deny that. There's some of me in Gollie, and a lot of Kate in Bink."

The illustrations, by San Francisco artist Tony Fucile, sprang from childhood photos of the two authors.

"I have yet to talk to Tony," DiCamillo said. "I've never met him, and yet he captures me -- that is, Bink -- kind of perfectly, to the point where anybody who knows me is convulsed with laughter when they see it."

A smooth collaboration

DiCamillo and McGhee worked on the stories three times a week in two-hour sessions, and they agreed not to work on them at any other time, not even through quick e-mails. "It just happened best when we were in the presence of each other and we could just sit and look at each other and pace around and work things out then and there," McGhee said. "We just wanted to keep everything high-energy and flowing and not dilute it.

"We polished and refined and shaped and changed everything completely together. It was such a collaboration. I've never done anything like that."

There was no conflict or disagreement. "We're both strong personalities, I think," said DiCamillo. "But we're also both good workers. And I think, at the risk of sounding really ridiculous, we both kind of honor the story. It was just kind of like this joyful process of discovering those girls, and then thinking about what they would get into next -- and how Bink would horrify Gollie."

The book has no more than a scattering of words on any page, which might seem like a pretty light load for one writer, let alone two. But both said the book simply would not have come about if only one of them had attempted it.

"It's interesting to me, the energy that you tap into with somebody else," DiCamillo said. "It couldn't have happened without two of us."

Said McGhee, "Quantity is neither here nor there in terms of easiness. It's the challenge of that absolute brevity, not a single word wasted, the rhythm and cadence and the punch line -- that is the hardest kind of writing."

And just as the relationship between Bink and Gollie brings out the best in both girls, so did the writing relationship between McGhee and DiCamillo bring out new and wonderful things for them. DiCamillo had always been a slow, solitary writer, but working on "Bink and Gollie" showed her that she can work in other ways.

"It was a great process for me," she said. "One, because it took away the fear, which is always there for me when I write, and two, because it showed me that I could work in a different way. And, three, it just made me think I should try different things. It opened up doors."

DiCamillo recently collaborated on a story with New York writer Jon Scieszka. Now she's working on an anthology in honor of the 25th anniversary of Chris Van Allsburg's enigmatic picture book "The Mysteries of Harris Burdick." Several authors were each asked to write a short story based on the book's illustrations.

"If I hadn't had the 'Bink and Gollie' experience, I would have said no to this, because I would have thought that's not the way I work."

And there's also, of course, the possibility of more collaboration with McGhee -- maybe Bink and Gollie, Part Two.

"We have lots of ideas for other stories," McGhee said. "Right now we're focusing on this one, but we hope there will be more."

Usually by the time a book is published, the author is sick of it. "You're usually just like, 'I've had it,'" DiCamillo said. "But that book continues to bring me joy. I can still laugh out loud when I read it. It's a happy thing for me to have such a happy book."

Laurie Hertzel is the Star Tribune's books editor. She is at 612-673-7302.