If you weren’t beyond excited already for The Professor and the Madman, a film adaptation of a book about the creation of the Oxford English Dictionary, get hyped, because Game of Thrones’ Natalie Dormer has joined a cast that includes Sean Penn and Mel Gibson.

According to The Hollywood Reporter, Farhad Safinia, who wrote the script for Gibson’s Apocalypto, is set to direct the project. Apparently Gibson is really enthusiastic about the dictionary or something, because he’s been trying to get this project going since 1998.

Gibson will play the titular Professor James Murray, who decided to compile a dictionary of every word in the English language in 1857. The madman is Dr. W. C. Minor (Penn), who submitted more than 10,000 entries to the dictionary while he was also an inmate at a mental hospital for the criminally insane. He was put there because he killed the husband of Dormer’s character. A romance between the two ensues, because, you know, if you can’t have your husband back, his killer is the next best thing.

Dormer’s run on Game of Thrones has, let’s just say, ended, and she’ll soon start production on In Darkness (no, not another Star Trek film), whose script she co-wrote with her director and fiancé Anthony Byrne (Ripper Street, Mr Selfridge).