The 55-year-old Queen of Pop hasn't had the best of luck with her previous directorial efforts -- 2011's W.E. and 2008's Filth and Wisdom -- but she's clearly passionate about the novel.
"Read this Book! An incredible journey! A Beautiful LOVE story!" Madonna wrote last year.
Walker, daughter of The Color Purple scribe Alice Walker, will co-produce the film, which centers around an American student who falls in love with a Muslim man on an island off the coast of Kenya.