Ian McKellen plays an older Sherlock Holmes in the new film "Mr. Holmes," who revisits an unsolved case that forced him into retirement.

"The case, which was to be my last, made me see that human nature was a mystery that logic alone could not illuminate," McKellen says in the first official trailer for the new Sherlock Holmes film.

Holmes returns home to Sussex, England from Japan in 1947, after bearing witness to the nuclear destruction in World War II. He now tends to his bee colony at his estate, also home to his housekeeper and her young son, Roger.

He remains troubled by a 50-year-old case, but struggles to remember all the evidence and people involved. He enlists the inquisitive Roger to help him put the case to rest as he fights his diminishing memory.

The film directed by Bill Condon ("Kinsey" and "Dreamgirls") also stars Laura Linney and Milo Parker, in only his second film.

"Mr. Holmes" has not announced a U.S. release date.

Watch the trailer below: