Sydney Sweeney, Amanda Seyfried set to star in 'The Housemaid'

A movie adaptation of Freida McFadden's The Housemaid is in the works, and Sydney Sweeney and Amanda Seyfried are set to portray Millie and Nina.

Nina and her husband, Andrew, hire Millie to work and live in their home.

"I can pretend to be whoever I like," Millie says in a book synopsis. "But I'll soon learn that the Winchesters' secrets are far more dangerous than my own..."

McFadden is an executive producer on the project.

"I can't even express how excited I am..." she wrote on social media. "Lionsgate has come up with the absolute perfect cast and director, and I am just so grateful! I mean, Sydney Sweeney, Amanda Seyfried and Paul Feig... mind blown! I'm so honored and thankful to all my readers who helped make this dream come true!"

Sweeney, Seyfried and Alex Young will also executive produce, Variety reported.

The casting was also a source of excitement for Lionsgate executives.

"Part of the fun of the book was imagining the cast while we read it," said Erin Westerman, co-president of Lionsgate Motion Picture Group. "And Sydney Sweeney and Amanda Seyfried are perfect for Millie and Nina -- they're both mysterious, nuanced, and incredibly skilled at becoming characters who don't reveal everything right away."

Sweeney posted a video on Instagram that shows her reading the book.

"Tell me about yourself, Millie," she captioned the clip.