The Magician's Apprentice (1) (S09E01)

Clara finds herself in a dire situation as a strange alien power freezes the skies over Earth, leaving her desperate for the Doctor's assistance. However, his whereabouts are shrouded in mystery, and he appears to be avoiding something from his past. As old foes resurface, the stakes grow higher, and both the Doctor and Clara must confront their darkest fears. With survival hanging by a thread, the duo faces challenges that seem insurmountable.