Guest Stars Rupert Graves as DI Lestrade Una Stubbs as Mrs. Hudson Mark Gatiss as Mycroft Holmes Andrew Scott as Jim Moriarty Russell Tovey as Henry Knight Amelia Bullmore as Dr Stapleton Will Sharpe as Corporal Lyons Sasha Behar as Dr Mortimer Chipo Chung as Presenter Stephen Wight as Fletcher Clive Mantle as Dr Frankland Gordon Kennedy as Gary Kevin Trainor as Billy Simon Paisley Day as Major Barrymore Rosalind Knight as Grace Sam Jones as Young Henry
