User blog comment:MasterCharmander13/DWA Mystery Season Teaser/@comment-28119130-20150701070234

Cool teaser! Who is 'the one'? The Doctor? Stormaggedon? Although I think that arc will be ended in the Series 4 finale. The person speaking... The Master or the Joker? Somehow I think this teaser will be for Series 6. Very exciting! :)