A ex-Downton Abbey star has undergone a dramatic transformation for an upcoming sci-fi action film. Wingard told Entertainment Weekly that Stevens' character was actually based on a real person called Hans Kammler. What to Read NextStevens and Wingard have collaborated numerous times before, with their first project together being The Guest (2014). Onslaught has been given a US release date of 4 September; however, a UK release date is yet to be confirmed. Visit our Streaming Guide now to see at a glance where you can view ALL your favourite shows and movies.