George C. Scott plays a man who, because of an incomprehensible loss, develops a new way of dealing with the world. He thinks he's Sherlock Holmes, and he collects newspaper clippings that lead him to the conclusion that there is indeed a malevolent force in the world, and that force is Moriarty. Naturally everyone thinks he's nuts, but his analyst, Dr. Watson (Joanne Woodward) is gradually drawn into his world. Scott's character also goes to Randolph Scott movies exclusively because the Good Guy always beats the Bad Guys in the black hats. I can't see anything wrong with that.
I haven't seen this movie in awhile, but I really do like it. Just about everything in it worked for me (I'm in a minority here, so be warned). There's a great cast, and not a weak link in it. The ending really bowled me over. I can still run it in the theater in my head, and I do, now and then.