If you’ve got too many pre-conceptions of just how a Sherlock Holmes movie should pan out, then it’s probably best that you check them in before popping this latest version in your player. Starring Robert Downey Jr. in the title role and accompanied by Jude Law as Watson, this film dispenses with some of the conventions of Holmes, and instead starts turning him into something of a period action hero.

Downey Jr. is more than up to the challenge too. Early scenes in Sherlock Holmes are more Fight Club than sleuth-influenced, with the hand of director Guy Ritchie behind the camera being very clear. But the film soon settles down and starts to have some fun, with the able assistance of Mark Strong and Rachel McAdams, among the supporting cast.

Yet this is Downey Jr.’s show, and he doesn’t waste the opportunity. He’s an engaging leading man at the worst of times, and he’s clearly having a ball here. What’s more, it’s immensely satisfying when his Sherlock Holmes gets down to the business of solving crimes, even though there are some really quite impressive action sequences to work through first.

There are problems, of course. There’s not enough flesh on the bones of some of the characters, and the early part of the film feels very different from the latter stages. But there’s solid groundwork here for the inevitable franchise, and watching Downey Jr. reprise the role of Sherlock Holmes over the next few years should be really quite good fun too. --Jon Foster