So, this is happening. In spite of the fine cast featuring every Irish actor ever, I'm going to go out on a limb and say that a metafictional novel about an author's characters coming to life and interacting with the real world is unlikely to make a good movie.
Why do filmmakers have such a compulsion to film unfilmable books? Why don't they pick on unfilmable plays, or comics or paintings for a change? Does the novel still have such a high place in our culture that movie makers have to try it "because it's there" like Mount Everest?
TOP SIGNS THAT A BOOK IS PROBABLY UNFILMABLE
1. It is just a series of events or arresting images without much of a narrative through-line (Orlando, Naked Lunch, Even Cowgirls Get the Blues, Catch-22). Plotless movies can work, but the director has to set the rhythm to keep them from becoming either dull or frenzied, hard to do with someone else's material.
2. It's mostly about the author's style or avant-garde techniques (Bonfire of the Vanities, Tropic of Cancer, Crash, Ragtime). There's no way the director can capture that in a different medium.
3. Most of the action happens inside the characters' heads (Housekeeping, anything based on the work of Henry James). If you are not making a film noir, narration has to be used very sparingly, or it becomes an audiobook with pictures.
4. Magical realism. (Mermaids, Household Saints, anything based on the work of Gabriel Garcia Marquez). In books, the reader has the choice to believe it really happened, it's just a legend/folklore, or somewhere in between. There's no way to convey this in a movie.
So, Brendon Gleeson, I'm sorry, but I must put a curse on you. And if anyone tries to make a movie out of the following books, I will find some way to punish you: Call It Sleep, Libra, Pale Fire, Loving, Two Girls Fat and Thin.
What's on your unfilmable list?