It is 1947, and the long-retired Sherlock Holmes lives in a remote Sussex farmhouse with his housekeeper and her young son. He tends to his bees, writes in his journal, and grapples with the diminishing powers of his mind.

But in the twilight of his life, as people continue to look to him for answers, Holmes revisits a case that may provide him with answers of his own to questions he didn't even know he was asking - about life, about love, and about the limits of the mind's ability to know.