Ian McKellen was surely made to play Sherlock Holmes—that lanky figure and cultivated voice are ideal for the deerstalker hat, the pipe, and the highbrow cogitating. As it happens, all three attributes are challenged in Mr. Holmes, Bill Condon’s film about the waning days of the world’s greatest consulting detective. Holmes, now 93 and long retired to the countryside, irritably brushes aside the cap and the pipe as the fancies of those stories Dr. Watson used to write. More pressingly, Holmes’ mind is fading. As he loses his memory, he tries to put down in writing what happened in his last case, some 30 years ago. He’s forgotten the details, but he knows that something went terribly wrong.