Perhaps even the great detective himself could not solve the mystery of why Sherlock Holmes holds the Guinness Book of World Records title for having been portrayed on screen than any other fictional character, with more than 75 actors in more than 200 movies. And it would be hard to find any movie and television detective who does not draw something from Holmes’ mastery of the power of observation (“Lie to Me,” “The Mentalist”). There is something endlessly fascinating about the idea that someone could look at us and see what others are hiding from us, and even about the idea that he could see what we are hiding, too.

So here we are again with another Sherlock Holmes, this one from Robert Downey, Jr. and director Guy Ritchie. And that means an edgier, grubbier, somewhat younger Holmes. While stage and screen versions of the stories have generally focused on Holmes as a sort of hyper-controlled super-brain with little emotion or physicality, this version expands on a reference in the original Arthur Conan Doyle texts to Holmes’ being adept at “baritsu,” a form of martial arts and has a two-fisted Holmes who fights bad guys and even mixes it up just for fun. It also focuses on the books’ notion that Holmes was good at detection because he was bad at everything else and that unless he was completely involved in a case he considered worth his attention he does not have any other way to interact with the world.

Dr. Watson, portrayed as a bit stuffy and more of a biographer than a partner for Holmes, in this version is played by the not-at-all-stuffy Jude Law as someone who struggles with his own demons (a gambling problem) and loves the adrenaline rush as well as the sense of justice and the fun of fighting along side his talented friend. But things are changing. He has met a woman he wants to marry and that means moving out of the flat on Baker Street he shares with Holmes and less time for crime-fighting.

Downey is always at his considerable best with a character who has some boundary issues and his Holmes is as taut as the violin strings he plucks between cases. His eyes are the most expressive on screen since Al Pacino, large, liquid, knowing. Downey conveys the almost compulsive, almost Aspergers aspects of the Holmes character. In one scene, he waits for Watson at a restaurant, unable to stop noticing the dark, the sad, the painful at the tables around him. He seems to drink it all in through his eyes, ears, and pores on his skin. And his need to understand and conquer the worst of humanity outside him seems connected to a struggle within himself — and between him and Irene Adler, for Sherlock Holmes, Conan Doyle wrote, “the woman.” Here she is deliciously played by Rachel McAdams, suiting his description of Irene as having “the face of the most beautiful of women, and the mind of the most resolute of men,” and fetching in bustle and boy-clothes.

Production designer Sarah Greenwood has done a magnificent job of creating Victorian London and part of the fun is seeing some of the now-iconic structures still under construction — always a handy place for a fight scene, too. Ritchie’s kinetic camerawork lends a muscular energy that keeps the story from feeling antique. And getting used to a young, energetic Holmes who can throw a punch is not as difficult as you might think.

But other parts of the movie do not work as well. Ritchie, whose best films celebrate the gritty underworld of big and small-time crooks, seems to be more comfortable for some of the mid-level thieves, arsonists, and hoodlums Holmes and Watson run into, and every time they leave the scene a little bit of the life of the film goes with them. Mark Strong is not given nearly enough to do as the villain (titled, of course) and the mystery is not clever enough to make the resolution satisfying. You don’t have to be a super-sleuth to see the holes in the plot. Downey is better detecting than he is trading odd couple banter with Law, but so would anyone. Who could have imagined that in a Sherlock Holmes movie the fight scenes replacing the deductions would ring truer than the dialogue replacing “Elementary, my dear Watson?”