Business must be brisk in the murky world of detectiving, if Sherlock Holmes' current workload is anything to go by. Not only is he back on the small screen with the return of the series Sherlock (starring Benedict Cumberbatch and Martin Freeman) on New Year's Day, but he returns to the big screen too with Guy Ritchie's blockbusting sequel, once again starring Robert Downey Jr. and Jude Law.

It appears that the long-running partnership between Sherlock Homes (Downey Jr.) and his faithful companion Dr Watson (Law) is finally coming to an end. Watson, you see, is about to get married.

It comes at an awkward time however, as Holmes finds himself facing one of the greatest criminal minds in his nemesis Professor James Moriarty (Jared Harris). Moriarty has a plan to start a war to end all wars, and it appears only Holmes can stop him. Not only that, but Moriarty has also promised that with Holmes meddling in his affairs, he has no choice but to stretch his wrath to include no other than Watson.

With Holmes on the case all over Europe, this deadly game of theirs is well and truly afoot.

It was only a matter of time before Sherlock's most famous adversary would surface in Richie's re-invented world. And although Harris wouldn't necessarily be considered first choice for the role, he brings an authentic balance of charm and deviance to the part.

You think I'm Sherlock Holmes? Oh my, what a mistake, for you see I'm a lady!

Downey Jr. pretty much picks up from where he left off in the last film, imbuing his Sherlock with a curious concoction of manic-ness and tomfoolery. His not-so-cunning disguises are amusing, and yet it appears to be more of a nod to a certain Inspector Clouseau than Holmes.

The chemistry between Holmes and Watson is also still there. Another outing for the pair has clearly given them more time to work on developing their intimate relationship even further.

Where the film takes a stumble however, is in the script. For some unknown reason, the film has been written by a couple (Michele & Kieran Mulroney) who have no previous experience writing for a big Hollywood film. And it shows. The story is a rambling wayward mess.

It certainly made sense to extend the adventure outside of ye olde M25, but the script really struggles to come up with cohesive reasons for Holmes and Watson journeying to Europe. It loosely involves gypsies, of which star of the original The Girl with the Dragon Tattoo trilogy Noomi Rapace plays one. However it turns out to be such a flimsy foil on which to balance the entire film's story, that after an hour or so in, it's clear that it just can't take the weight. It would have made more sense if Ritchie made the film a silent one and just had his Holmes and Watson running around Europe to the Benny Hill theme.

The film's plot isn't the only thing that's dull in places; the whole thing appears to be shot using a new technique of Ritchie's called Grey-O-Vision. Either that or it suffers terribly from colour allergies.

It's a shame as there are some nice performances throughout, particularly from Law who doesn't get in the way of Downey Jr's limelight, but does just enough to get himself noticed.

Overall A Game of Shadows is a backwards step for the franchise. If there's to be a third outing, they will need to focus on a very back-to-basics story to succeed. After all, as the BBC TV series has proven, story is king. It's that elementary.