In the first trailer for "Mr. Holmes," Ian McKellen plays an aging Sherlock Holmes, who must solve his last case even as his memory begins to fade.

With the help of his housekeeper Mrs. Munro (Laura Linney) and her son Roger (Milo Parker), Holmes must conduct a final investigation to close an unsolved case that forced him into retirement. The film is based on Mitch Cullin’s novel "A Slight Trick of the Mind," which finds a 94-year-old Sherlock Holmes returning from Japan after its nuclear destruction.

"Mr. Holmes" is scheduled to debut later this year. Check out the trailer below.