Arthur Conan Doyle’s master detective became one of the great heroes in genre fiction precisely because he was so freakish: cold and methodical, Holmes was the dark underbelly of Victorian rationalism, his intellect so overdeveloped that he couldn’t relate to anyone. The very idea of handing him over to professional lad Guy Ritchie (who directed Snatch and Lock, Stock and Two Smoking Barrels), to be played as a punch-throwing quipster by Robert Downey Jr., is so profoundly stupid one can only step back in dismay. The plot of this thudding blockbuster involves a satanic priest (Mark Strong) scheming to conquer the UK, and it gives Holmes and Dr. Watson (Jude Law) ample opportunity to bust out their street-fighting skills. Rachel McAdams shows up as Irene Adler, the woman who outfoxed Holmes in “A Scandal in Bohemia”; here she gets the better of him by drugging his wine and handcuffing him to a bed nude for the maid to find.