The Shadowhunter's Codex is a companion book to Cassandra Clare's The Shadowhunter Chronicles. The book was authored by both Clare and her husband, Joshua Lewis, and was released on October 29, 2013. The Shadowhunter's Codex is written in the form of an illustrated handbook: a facsimile of the one given to Clary Fray, the protagonist of The Mortal Instruments series. Source: Wikipedia (en)