This is the most fun you’ll have at the movies all year, unless you’re having what Holmes (Robert Downey Jr.) is having. Downey Jr. plays the brainiac detective like an overheating machine—what cools him off is a puzzle. When director Guy Ritchie puts us in his head, we’re instantly overwhelmed. Against his will, he’s barraged by every detail, every look, every speck—these loose ends without a direction, and after they whip him into a headache, all he can do is close his eyes. This is Holmes the action hero and when he throws a punch, he maps it first from feint to physical and mental recovery time. In the books, his physical feats were often offstage; Conan Doyle would spirit him away once he was certain of the villain and bring him back to the page only to talk about what ass-kicking he’d just done. Here, we see him take down a boxer in a betting fight. This re-imagining is messy, smelly and mean, and crammed with a solid cast in which Holmes’ bromance with Watson (Jude Law, well-cast) far outshines his flirtation with Irene Adler (Rachel McAdams), who looks great in bustles but never cranks up the heat. When the trio works together, they’re out to stop the evil Lord Blackwood (Mark Strong) from killing beyond the grave. More often, they’re out to undermine each other as Hans Zimmer’s jaunty klezmer score keeps the party going. And everyone’s humming for a sequel.