The film stars Ian McKellen as Sherlock Holmes, Laura Linney as his housekeeper Mrs. Munro and Milo Parker as her son Roger.

Set primarily during his retirement in Sussex, the film follows a 93-year-old Holmes who struggles to recall the details of his final case because his mind is slowly deteriorating.

In 1947, the long-retired Sherlock Holmes, aged 93, lives in a rural Sussex farmhouse with his widowed housekeeper Mrs Munro and her young son Roger.

Over time, Roger's prodding helps Holmes remember the case (shown in flashbacks); he knows he must have failed somehow, as it resulted in his retirement from the detective business.

Almost 30 years earlier, after the First World War had ended and Watson had married and left Baker Street, Thomas Kelmot approached Holmes to find out why his wife Ann had become estranged from him after suffering two miscarriages.

A second series of flashbacks recounts Holmes' recent trip to Japan, where he met a supposed admirer named Tamiki Umezaki who had told him of the benefits of prickly ash.

His closeness to her son Roger is another source of tension, as the boy is becoming dissatisfied with his family's lowly status and increasingly distant from his barely literate mother.

As they sit in the waiting room, Holmes tells Mrs Munro that he was too fearful and selfish to open himself up to Ann Kelmot and to give her the comfort that she needed.

As Roger begins to teach his mother how to care for the bees, Holmes emulates a tradition he saw practised in Hiroshima: creating a ring of stones to serve as a place where he can recall the loved ones he has lost over the years.

On 5 September 2013, it was announced that Mitch Cullin's 2005 book A Slight Trick of the Mind would be adapted into a film, with Ian McKellen as a long-retired Sherlock Holmes.

[4] On 9 July Hiroyuki Sanada was added to the cast to play Matsuda Umezaki, a prickly ash plant enthusiast whom Holmes visits in Japan.

[5] On 10 July, more cast were revealed, including Patrick Kennedy, Roger Allam, Phil Davis, Frances de la Tour, with Milo Parker to play Mrs Munro's son.

The website's consensus reads: "Mr. Holmes focuses on the man behind the mysteries, and while it may lack Baker Street thrills, it more than compensates with tenderly wrought, well-acted drama.