Guest Stars Rupert Graves as DI Lestrade Una Stubbs as Mrs. Hudson Louise Brealey as Molly Hooper Mark Gatiss as Mycroft Holmes Amanda Abbington as Mary Morstan Siân Brooke as Eurus Holmes Lindsay Duncan as Lady Alicia Smallwood Tanya Moodie as Ella Simon Kunz as Sir Edwin Paul Chequer as DI Dimmock Charles Edwards as David Welsborough Sacha Dhawan as Ajay Eleanor Matsuura as DI Hopkins Daniel Hoffmann-Gill as Gold Teeth Man Amanda Root as Emma Welsborough Marcia Warren as Vivian Norbury Albert Magashi as Karim Gabrielle Glaister as Ambassador Eiry Thomas as Stewardess Edward Judge as Craig David Colbourn as Male Client Rob Callender as Charles Welsborough Aleksandar Mikic as Guard Andrew Bone as Jack Sandeford James Holmes as Plane Passenger Hattie Ladbury as Female Client Neal Barry as Ray Kingsley Richard Syms as Vicar Harry Gostelow as Husband