"Young Sherlock" Season 2 has started production, and Prime Video on Wednesday announced the addition of four new series regulars. Sophie Skelton ("Outlander"), Aidan Gillen ("Game of Thrones"), Olivia Williams ("Dune: Prophecy"), and Indira Varma ("Dune: Prophecy") have joined the YA drama, alongside returning series regulars Hero Fiennes Tiffin (Sherlock Holmes), Dónal Finn (James Moriarty), Natascha McElhone (Cordelia), Holly Cattlee (Edie), and Max Irons (Mycroft). Character details are being kept under wraps. Guy Ritchie will return to direct the season premiere. A release date has not yet been announced.