Usagi and Inspector Ishida join forces once again as they embark on a mission to track down and uncover the importance of a foreign book. The duo, desperate to solve the mystery, are forced to undertake unusual measures as well as enlist the help of a few surprising sources to get the information they require.

Collects Usagi Yojimbo: The Hidden issues #1-#7, in a limited-edition hardcover signed by Stan Sakai.