The actress plays the brother of Texas Ranger John Reid in director Gore Verbinski's Western adventure.
The Luther star joins Liam Neeson and Dan Stevens in writer-director Scott Frank's upcoming crime thriller.
The British actresses are the top two contenders for this sought-after role in the upcoming Marvel Studios sequel.
John Lee Hancock is directing this story about how Mary Poppins author P.L. Travers reluctantly let Disney adapt her beloved novel.