Ian McKellen shares photo as 93-year-old Sherlock Holmes

British actor Ian McKellen has revealed the first photo of himself playing a 93-year-old Sherlock Holmes in a new movie.

Filming has begun on "Mr. Holmes," which imagines the famous sleuth in his old age as a retiree living in seclusion by the English seaside in 1947. The movie, based on Mitch Cullin's 2005 novel "A Slight Trick of the Mind," sees Holmes struggling with a failing memory and revisiting one final unresolved mystery.

The 75-year-old McKellen posted a picture of himself in costume as Holmes on his Twitter account this week, saying: "Over 70 actors have previously played Sherlock Holmes. Now he's 93 years old and it's my turn."

Laura Linney, his co-star, plays Holmes' housekeeper.

The film is directed by Bill Condon ("Dreamgirls," "The Fifth Estate"), who had previously worked with McKellen on 1998's "Gods and Monsters" and with Linney on 2004's "Kinsey" and Showtime's "The Big C."

McKellen, who plays Magneto in the "X-Men" movies, is the second actor from the Marvel Films Universe to step into the role of Holmes. "Iron-Man" and "Avengers" star Robert Downey, Jr. previously played the British detective in 2009's "Sherlock Holmes" and the 2011 follow-up, "Sherlock Holmes: A Game of Shadows."

"Mr. Holmes" is due for release next year.