Two Doctors stranded in an Arctic snowscape, refusing to face regeneration. Enchanted glass people, stealing their victims from frozen time. And a World War One captain destined to die on the battlefield, but taken from the trenches to play his part in the Doctor's story. An uplifting new tale about the power of hope in humanity's darkest hours, Twice Upon a time marks the end of an era. But as the Doctor must face his past to decide his future, his journey is only just beginning