Knives Out is titled Glass Onion: A Knives Out Mystery.The director revealed the title in a thread on Twitter, where he explained how novelist Agatha Christie influenced his approach to the sequel.“Something I love about Agatha Christie is how she never tread water creatively,” Johnson wrote. “I think there’s a misperception that her books use the same formula over and over, but fans know the opposite is true.“It wasn’t just settings or murder methods, she was constantly stretching the genre conceptually.