It follows the story of live-in nanny Rowan Caine, who slowly discovers her dream placement at a high-tech 'smart' house in Scotland is actually a nightmare that will end in death and imprisonment.
The Turn of the Key will fall under the Working Title umbrella, with Minghella previously penning and directing the 2018 Elle Fanning film Teen Spirit and adapting The 9th Life of Louis Drax for the screen.
It will mark Bell's first writing credit and is the fourth Ruth Ware novel to be optioned for the screen, following In a Dark, Dark Wood, The Woman in Cabin 10 and The Lying Game.
The Death of Mrs. Westaway and One by One have yet to be optioned.
Minghella stars as Nick in The Handmaid's Tale and has also starred in Spiral: From the Book of Saw and The Mindy Project.
Bell starred as Bernie Taupin in Rocketman.
He also recently starred in Without Remorse, Film Stars Don't Die in Liverpool and Fantastic Four.
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