WATCH: Ian McKellen in the First Trailer for Mr. Holmes

Ian McKellen has already portrayed great literary characters like Gandalf and Magneto - yes, comic books are literature - and now he's adding another famous name: Sherlock Holmes.

In Mr. Holmes McKellen plays an elderly version of the character, made famous by Sir Arthur Conan Doyle, who has just returned from Japan in 1947 after seeing the devastation of nuclear war. Holmes must face the reality of his diminishing mind with the companionship of his housekeeper, Laura Linney, and her son, who idolizes him.

Together, Holmes and his young protege work to solve the mystery that forced Holmes into retirement before he runs out of time.

Watch the trailer below.