As reported by VARIETY and confirmed by the comic's author, Willow and Jaden Smith are attached to star in Warners' AMULET, an adaptation of Kazu Kibuishi's graphic novel.
Akiva Goldsman's Weed Road, Will Smith and James Lassiter's Overbrook Entertainment are producing.
The story is about a brother and sister who move into their late great-grandfather's house after their father dies, and must use an amulet to rescue their mother from an underground beast.
The Scholastic series has five book planned, with the second to be released this year.
"I never imagined we would be moving so quickly on the film side of things," Kibuishi wrote on his blog. "I better get the next few books done a little faster! Anyway, I'm really looking forward to meeting the Smiths. I've been a huge fan ever since the early FRESH PRINCE days, and seeing the kind of work they've been doing lately, I can see that we'll be on the same wavelength on this project. This is going to be cool."
Willow is 7 and will appear in Picturehouse's June release of KIT KITTREDGE: AN AMERICAN GIRL MYSTERY. Nine-year-old Jaden appeared with his dad in THE PURSUIT OF HAPPYNESS and will be in Fox's upcoming THE DAY THE EARTH STOOD STILL.