EXCLUSIVE: Douglas Henshall (Shetland) and Sienna Guillory (Resident Evil franchise) are taking on key roles in mystery horror One Of Us, alongside Kit Conor (Heartstopper), Callum Woodhouse (The Durrells), Charlotte Hope (The Spanish Princess), Siobhan Fallon-Hogan (Rushed) and Ian Beattie (Game Of Thrones).