Laura Linney is joining Ian McKellen in Bill Condon’s Sherlock Holmes tale “A Slight Trick of the Mind.”

The casting marks the fourth collaboration between Condon and Linney, who starred in “Kinsey,” “The Fifth Estate” and the pilot episode of “The Big C.”

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Linney will play Mrs. Munro, the housekeeper to Sherlock Holmes, played by McKellen. Hattie Morahan of PBS’ “Bletchley Circle” has also been cast.

Production is set to begin in the summer in the U.K. Producers are Anne Carey through her Archer Gray Prods. and See-Saw Films.

Exec producers are Icon/AI Film CEO Aviv Giladi, Len Blavatnik, BBC Films’ Christine Langan and Archer Gray’s Amy Nauiokas. BBC Films is a co-financier.

Jeffrey Hatcher adapted the screenplay from Mitch Cullin’s novel with Holmes in a contemplative frame of mind in 1947 England. As he deals with the diminishing powers of his mind, Holmes comes to rely upon the housekeeper’s son as he revisits the circumstances of the unsolved case that forced him into retirement.

Condon teamed with McKellen on “Gods and Monsters” and won an Oscar for adapted screenplay. His directing credits include “Kinsey” and the final two “Twilight” films.

Linney is represented by ICM Partners and Brillstein Entertainment Partners.  Morahan is represented in the U.S. by ICM and Authentic Talent Management.