He'll return to his Captain Jack Harkness, which he reprised in January after a 10-year absence. "In the upcoming special titled 'Revolution of the Daleks,' Captain Jack will be on hand to help the fam as they discover a disturbing plan forming involving one of the Doctor’s most feared and dangerous enemies, the Daleks. With the Thirteenth Doctor locked away in a space prison, will Captain Jack be able to help save planet Earth?" BBC said in a statement. Watch the trailer.