A real-life mystery is brewing at Western University after a professor found a cryptogram tucked inside the pages of a library book – the first of many strange notes ultimately discovered at the London, Ont., campus.

At least 15 messages, all written in "Wingdings-esque" font and found inside library books, have been uncovered since the original note was found.

Earlier this month Mike Moffatt, an assistant professor of business, economics, and public policy, was perusing book titles on the third floor of the D.B. Weldon Library in the economics and political science section.

He took out a book -- "International Economics: Trade and Investment" by Soren Kjeldsen-Kragh -- and was surprised to find a hidden message and a plastic leaf concealed inside a plain white envelope.

"It fell out of the book and I picked it up," Moffatt writes on his blog on March 10.

"I opened the envelope and discovered the following note and plastic leaf. The leaf was not attached to the note in any way."

The baffled professor, who has offered to pay $100 to anyone who can crack the cryptic messages' code, has since received a number of emails detailing similar discoveries in the same library.

In each of the envelopes, an item, such as a feather or a gem stone, accompanies the mysterious note. It appears to relate to the symbols used in the message. A picture of a household item, such as a vase or a table, is also featured on the front of the notes, and a web address is printed on the back. The URL links to an empty blog, titled "DBW Stack," which has been viewed more than 1,550 times.

Moffatt has had the cryptic notes analyzed, noting there are more than 40 different symbols used.

"This looks like more than a straight letter substitution," he writes in his blog. "The font is Wingdings-esque, but appears to be custom made."

There are many theories on the origin of the coded messages, but according to The Gazette, the university's student newspaper, a popular one is that they were once part of a scavenger hunt.