Which novel influenced the movie in which Hattie Morahan played Ann?
Hattie Morahan: Harriet Jane "Hattie" Morahan (born 1978) is an English television, film, and stage actress. Hattie Morahan:  Her roles include Alice in "The Bletchley Circle", Gale Benson in "The Bank Job" (2008), Ann in "Mr. Holmes" (2015), Rose Coyne in "My Mother and Other Strangers" (2016), and Agathe/The Enchantress in "Beauty and the Beast" (2017). Mr. Holmes: Mr. Holmes is a 2015 British–American crime drama mystery film, directed by Bill Condon, based on Mitch Cullin's 2005 novel "A Slight Trick of the Mind", and featuring the character Sherlock Holmes.
A Slight Trick of the Mind