Guest Stars Emily Carey as Mary Conan Doyle Noah Jupe as Kingsley Conan Doyle Blake Harrison as Lyman Biggs James Lance as Barrett Underhill Sebastian Croft as Newsie Dean Forster as Herbert Ogilvie Tommy McDonnell as Nigel Pennington Mary Healey as Mrs. Blake Natasha Sparkes as Sophie Helen Millar as Isobel Underhill Tereza Srbova as Natalia Kroshenko Scott Jenkinson as Spring Heel'd Jack Paddy C. Courtney as Gaines Craig Conway as Angus Tuttle Dritan Kastrati as Vladimir Patlinov