In Dark Dynasty, hacker Charlie Bradbury is enlisted to aid in the effort to decode Nadia's Codex and through it, the Book of the Damned. Using her Surface Tablet and pictures she took of the codex, Charlie endeavors to break the code Nadia put on her codex. At the Blackbird Motel, after painstaking effort, Charlie finally uncovers a way to read Nadia's Codex. Moments later, Eldon Frankenstein arrives looking for Charlie and the Book of the Damned. Rather than turn over her decoder to save her own life, Charlie uploads it into an email she sends Sam and destroys her Surface Tablet to keep the decoder out of the hands of Eldon. Eldon then murders her for it.
In The Prisoner, on the verge of ending the efforts to find a cure for Dean, Sam receives Charlie's email with her decoder. Sam shows it to Rowena who confirms that Charlie has successfully developed a way to break the codex and through it the Book of the Damned which will give them a way to find a cure for Dean.
In Brother's Keeper, Sam prints out Charlie's decoder and Rowena is able to use the codex in conjunction with it to break open the Book of the Damned and finds a spell that will remove the Mark of Cain from Dean's arm. After casting the spell, Rowena escapes with the decoder, the codex and the Book of the Damned.
In The Bad Seed, after capturing Rowena, the Winchesters are able to retrieve the decoder and the codex. However, Rowena doesn't have the Book of the Damned on her and later escapes. Sam tells Dean afterwards that without the decoder and the codex, Rowena should at least be slowed down.
In O Brother, Where Art Thou?, the Winchesters and Crowley enlist Rowena's aid to find a way to safely contact Lucifer in the Cage through the Book of the Damned. Rowena tells them that she will need the decoder and codex to perform the task and Sam grants her limited supervised use of both until they find the spell they need.
- Season 10
- Season 11
- Given what Charlie said while creating the decoder, it and the code in Nadia's Codex is connected to saint symbolism
- The attachment containing the decoder was labeled ForDean.doc. The email itself had 911 - see attached!!! in its "RE" line with the message "Sam, can't talk now. DL this file!"
- The printed version in Brother's Keeper shows that the decoder contains not just Charlie's cracked version of the code, but also her previous failed attempts as well.
- The pictures Charlie took while making the decoder include a picture of at least one page of the Book of the Damned, close-up pictures of pages of Nadia's Codex and a far away shot of two of the pages.
- The decoder is not seen or mentioned after O Brother, Where Art Thou? nor is the codex as Rowena is shown to be able to read the Book of the Damned on her own subsequently.