Legendary Pictures has finalized a deal with Stranger Things star Millie Bobby Brown to both star in and produce a movie series based on the Enola Holmes Mysteries novel series, written by Nancy Springer, which follows the title character, the sister of Sherlock Holmes. The 13-year-old actress will make her feature film debut in Legendary's Godzilla: King of Monsters, which is slated for release on March 22, 2019, and established the actress' relationship with the studio. No writer or director has been set for this adaptation as of yet, with Alex Garcia and Ali Mendes overseeing the project for Legendary.

The first book in the Enola Holmes Mysteries series, 2006's The Case of the Missing Marquess, begins on Enola Holmes' 14th birthday, when her mother inexplicably disappears. Her older brothers Sherlock and Mycroft Holmes deduce that their mother has abandoned them and left voluntarily, as they plan to send her to boarding school. After learning of their plans, Enola Holmes escapes to London, and learns after encoding a secret message that her mother has left to live with the Romani people, to escape the restrictive lifestyle of Victorian society in London. No plot details about this upcoming adaptation have been revealed yet so it isn't known how faithful this story will be to the books.

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There were six Enola Holmes Mysteries novels published between 2006 and 2010, including The Case of the Left-Handed Lady, The Case of the Bizarre Bouquets, The Case of the Peculiar Pink Fan, The Case of the Cryptic Crinoline and The Case of the Gypsy Goodbye. The first book, The Case of the Missing Marquess, and the fifth, The Case of the Cryptic Crinoline, were nominated for the Edgar Awards for Best Juvenile Mystery in 2007 and 2010. There is no indication as of yet whether or not author Nancy Springer will be involved with this adaptation. It seems unlikely that there will be any connection between this project and Warner Bros.' Sherlock Holmes movie franchise, starring Robert Downey Jr.

Millie Bobby Brown will serve as a producer through her PCMA Productions banner, marking her feature producing debut. The young actress has become a pop culture sensation through her role as Eleven on Netflix's Stranger Things, and we reported in November that the actress was offered the female lead role of Jill Pole in the new Narnia movie, The Silver Chair. There has been no indication since then that she was planning on accepting the role, but now that she is both starring in and producing this new project, she may not be available to play Jill Pole in The Silver Chair.

Millie Bobby Brown was discovered by a Hollywood talent scout in Orlando, who convinced her family to move to Los Angeles for her to pursue acting. Within months of her arrival, she landed the role of Young Alice on ABC's Once Upon a Time in 2013, and was then cast in Intruders a year later. After a few guest-starring spots on Modern Family, NCIS and Grey's Anatomy, she landed the breakthrough role of Eleven on Stranger Things, which was a cultural phenomenon when it debuted on Netflix in the summer of 2016. The young actress revealed in 2016 that she would love to play a young Princess Leia in a Star Wars spin-off, since many have noticed her resemblance to a young Carrie Fisher, although nothing official is in the works yet. Deadline broke the news on the Enola Holmes movie earlier today.