Edward Wozny is an investment banker with a few weeks to himself before taking a new assignment in London. To fill the time, he begins playing an underground computer game called MOMUS, and is also asked to catalog a collection of ancient books owned by the Duke and Duchess of Bowmry. It turns out that they want to know if their collection contains an ancient codex, a rare book from the 14th century. Edward hires a graduate student to help him, and she assures him that the existence of the book is just an old myth. He becomes more enthralled by the addictive nature of MOMUS, but when coincidences begin to emerge between the computer game and his hunt for the codex, he's off an a quest to discover the hidden truths. Lev Grossman's novel has received mostly positive reviews with the Boston Globe saying, "I guessed a few character motivations and a final plot twist long before they were revealed, but these are tiny quibbles in a book so inventive, so jaw-droppingly interesting, that I felt enthralled."