Dan Brown 'Inferno' companion planned for June 2013

Having already written "The Rough Guide to the Da Vinci Code," historian Michael Haag will be unraveling the mysteries of Dan Brown's next novel, "Inferno," due May 14, in "Inferno Decoded," announced for a June release.

The book is to furnish readers with an understanding of Dante's life and work, the historical Tuscan setting in which "Inferno" takes place, and a re-introduction to Dan Brown's recurring character, Robert Langdon.

"Robert Langdon's harrowing quest through Dante's underworld promises to be an exciting adventure of discovery. Florence makes a terrific setting. This is the place and Dante is the moment when the Renaissance begins," said Haag in a statement prepared by publisher Profile Books.

"I am excited to be close on the heels of Robert Langdon again and working with Profile Books on decoding the associations, the historical characters and the symbols in Dan Brown's new thriller."

There have been stirrings, too, from other Dan Brown guide authors: Simon Cox, author of "Cracking the Da Vinci Code" and "Hunting the Lost Symbol," promised his Twitter followers that details of his own guidebook would follow "very soon," while the Catholic World Report website teased its editor, Carl Olson, who was co-author of "The Da Vinci Hoax."