As fans of his bestselling Mysterious Benedict Society books know, author Trenton Lee Stewart loves a mystery – especially if it’s wrapped up in a puzzle or a secret code. But recently, Stewart found himself at the center of a social media mystery, via Goodreads, that he never could have imagined. The author has always elected not to participate in social media, largely because he worries that he would disappoint readers if he weren’t able to keep up with any accounts he might open. But Stewart’s visit to Goodreads a number of years ago surprisingly opened the door to a sleuthing effort on the part of some very devoted fans. On the eve of his book tour for his new standalone mystery-adventure, The Secret Keepers, Stewart gave Bookshelf the lowdown.

“Probably six or seven years ago, I had been on Goodreads from time to time to see what it was all about,” Stewart said. “And I saw that there was an option to sign up as a Goodreads author.” He did so, and then didn’t log in for a long while – years, in fact. “I checked back in September 2011 – exactly five years ago now – and saw that there were a bunch of friend requests and notes,” Stewart continued. “I thought ‘Oh no!’ because it’s always been a horror of mine that a kid might send a letter or note to me on one of these sites and never get a response.”

Stewart believed the best way to handle the situation was to provide a sort of blanket response to those on Goodreads. “I used the blog function to write a note to the people who had left comments, and in it I jokingly said, ‘I’m being mysterious... ’ and I figured that would cover it,” Stewart recalled. “I thought if they looked closely they would see that I wasn’t sending individual responses to anyone, so they’d know, ‘Oh he’s not just not answering me, but he’s not answering anyone.’ ”

Several more months passed, and then another author entered the picture. “I was contacted by the writer Pseudonymous Bosch because he had gotten a note via Goodreads from a kid asking if I was his secret identity,” said Stewart. “We are frequently accused of being each other – we have the same publisher and we’ve forwarded notes back and forth: ‘Here’s a person who thinks I’m you.’ ”

When Stewart headed back to Goodreads to have a look, this is what he found: “A man named Jim, who turned out to be a writer himself, made a cryptic joke in the comments section about my cryptic note, and almost instantly a group of kids – previously unknown to one another – decided there was a mystery to be solved and set out to crack it,” said Stewart. “For months they communicated via the comments section, turning over different clues – many of them provided by Jim, who, in my opinion, sweetly, responded to their pleas for help – and in the process becoming friends. They had obviously taken a cue from my books and assumed that if I talk about being mysterious, there must be a mystery to solve.”

Stewart said he was “blown away” by this whole development. “I was so touched that this group of kids formed a team in the comments section of Goodreads,” he recalled. “It was really sweet to see them asking about each other’s lives. I loved it, and I wanted to give them something. So I decided to write them a letter in the comments section. I created it in a high-faluting storytelling style and thought they’d enjoy that. But after they read the letter, which I thought would resolve their made-up mystery, they just kept right on going, asking, ‘Now what?’ ‘What’s next?’ It didn’t end!”

That was Stewart’s cue to step away from the site. “I pretty much bowed out and didn’t log in to Goodreads for a long, long, time,” he said, “but when I heard from my publisher that they wanted to do a giveaway of my new book on Goodreads, I logged in again. I was debating whether I should delete that earlier blog post. But then I saw that the kids had kept in some kind of touch with each other for years. And at the end of more than 1700 comments, one of the kids, Josiah, wrote a long letter about what this adventure had meant to him, and how it helped him through a difficult time in in his life.”

Excerpt from Josiah’s note:

In creating our own adventure, we expanded our own capacities for friendship and appreciation of literature. I regret not sending you a letter in the mail soon after that –I swore I would, I really swore I would. But postage from New Zealand is expensive, and it’s not like I have limitless amounts of money!

In the end, I must thank you most for giving a year or two of my childhood meaning. That was a time where I was struggling at school, and I didn’t want to go in the mornings, and I just wasn’t enjoying the experience.

You – and all the great friends I wish I had stayed in touch with after this – made one, two, or even three years of my life that much better.

So I have one thing to say to you, and I hope you understand that it is with the utmost sincerity:

Thank you. For everything.

For now, Stewart believes that telling the story of this five-years-in-the-making mystery is a good way to recognize the intrepid kids’ efforts. “I thought it would be nice thing for them to know that what they did didn’t just stay in the club, but it became public,” he said.

However, Stewart remains a social media holdout for the most part. “I’m just as nervous about it as I used to be,” he said. “I worry that I may be receiving some communication from kids that I won’t be able to respond to. It’s just not possible for me to do. But I kind of tiptoed in a little bit and mentioned the new book and the tour dates on Goodreads. If kids want to reach me, I wanted to make it a little harder for them. They have to find my P.O. Box address and use a stamp. I have been able to answer those letters, so far, even if it might take me a while.”

The Secret Keepers hits shelves September 27, and Stewart hits the road for a tour, with different legs of a national tour set to run through December. And who knows what new mysteries await him, in real life, and online?

The Secret Keepers by Trenton Lee Stewart. Little, Brown, $18.99 Sept. 27 ISBN 978-0-316-38955-6