The mystery surrounding Sony’s comedy take on Sherlock Holmes thickened yet further today with the news that Hugh Laurie and Ralph Fiennes have joined the cast.

The film – which has nothing to do with the Guy Ritchie reboots starring Robert Downey Jr and Jude Law, or the BBC series with Benedict Cumberbatch and Martin Freeman – is scheduled for release next year and is currently shooting in London.

Will Ferrell and John C Reilly reunite after Talladega Nights and Step Brothers in the leads, while Kelly Macdonald, Rebecca Nicholson and Rob Brydon have already been confirmed for supporting roles.

The Hollywood Reporter quotes sources who suggest both Fiennes and Laurie will play beloved canonical figures from the books of Arthur Conan Doyle. A Moriarty is not yet listed in the cast, but following Laurie’s villainous turn in The Night Manager, bets are off as to who is the more likely candidate.

Etan Cohen is writing and directing; his most recent credit was the Ferrell/Kevin Hart jail farce Get Hard.