<Li> Kelly Reilly as Mary Morstan, a governess whom Watson wishes to marry, causing a conflict with Holmes . </Li> <Li> Eddie Marsan as Inspector Lestrade, an investigator from Scotland Yard who hires Holmes to look into the murders . Unlike many previous adaptations, in this storyline Lestrade is not portrayed as a bumbling inspector, but is shown to be a rather competent officer (though he is relatively fed up with Holmes). </Li> <Li> Hans Matheson as Lord Coward, the Home Secretary, who is Blackwood's right - hand man and assisted Blackwood in all his murders . He was one of a small number of Blackwood's allies aware of his usage of technology to feign magical powers . </Li> <Li> Geraldine James as Mrs. Hudson, Sherlock Holmes' landlady . This is James' second Holmes film . She had also portrayed Dr. Mortimer's wife in the 2002 adaptation of The Hound of the Baskervilles . </Li>

Who is the bad guy in the hound of the baskervilles