Last week I received a mysterious letter. Isn't that a great opening line? Made even greater because it's true. Last week I received a mysterious letter.

The postmark was blurred. There was no return address. The envelope was buff-colored, my name printed in red Sharpie, in a lovely hand.

Inside was a white envelope. Written on one side was, "for you," and, on the other side, "follow your narrative urge!"

Curiouser and curiouser, as Alice would say.

I opened it, drew out a handwritten letter, a folded slip of paper and a $10 bill.

The letter read:

"Thank you for opening the envelope. The money is real. We are all parts of each others' stories. Let's create more together. Please join the project! Use the hints. Find me."

And a baffling clue:

"a site to see (haiku clue) robotic cranes dance/ in singapore. in taiwan / appears tornadoes!"

The folded slip of paper contained a snippet from something -- a short story, perhaps, or a novel.

What did it all mean?

The envelopes first started appearing in Atlanta in April, and expanded to 10 other cities this month -- Chicago, Baltimore, Detroit, San Francisco, Denver, Los Angeles, St. Louis, Washington, D.C., Jackson, Wyo., and Minneapolis.

In Atlanta, some arrived by mail, but many others were scattered around town -- tacked to utility poles, tied to park benches, dangled from trees, slipped between bottles of olive oil at the local Whole Foods, tucked into books or restaurant menus, left in public bathrooms. Each contained a clue, a snippet from a story or a book, and $10.

Perhaps a third of the 75 or so letters simply vanished into the ether with no response. But others produced an excited, if baffled, reaction as they were discovered.

Several recipients blogged about it, including folks at Creative Loafing, an alternative paper in Atlanta, who received an envelope in April, and the Chicago Reader, who received an envelope last week. (The Star Tribune blogged about it, as well.)

Someone set up a wiki page on the Web as a place where people could post clues and pool information ( Someone poked around on the Web and determined that the robotic cranes and the Taiwanese tornadoes were both 10 stories high, which seemed significant. And in June, someone found the project Web page, which contained no revelations, but which, when clicked on, caused two Facebook pages to go live. (Search on Facebook for "Narrative Urge" and "10 Stories High.")

The power of shared story

The folks behind the project will answer questions e-mailed to their Facebook pages, but they will not reveal their identities.

They describe the puzzle as an evolving literary art project and social experiment. An experiment in what? The power of story and storytelling, apparently; the ways our own life stories overlap, and the ways that art and literature can bring people together.

"As appreciators of the project struggle with the questions involved in it, they will come to understand more, or at least consider new ideas," Narrative Urge wrote in an e-mail. "Why would someone give away money and apparently want nothing but pleasure to come from it? How does money fit with art, or fail to? What's to be gained ... through following a 'narrative urge'?"

Anonymity, they said, was important. Without it, "Motives will quickly be assigned. ... Attention would stray from the project and its elements."

Still, art or not, there is no denying that the project is, at core, a puzzle -- a literary puzzle, an artistic puzzle, a puzzle still not yet fully solved. It is fascinating.

Narrative Urge wrote: "Fascination is good for you, for everyone."

Laurie Hertzel is the Star Tribune books editor.