Set years after the events of The Wolverine, the film features the cast of the original X-Men trilogy and X-Men: First Class.[33] The story, inspired by Chris Claremont and John Byrne's The Uncanny X-Men comic book storyline "Days of Future Past", features Wolverine going back in time to 1973 to prevent an assassination that, if carried out, will lead to the creation of a new weapons system called the Sentinels that threatens the existence of mutants—and, potentially, all of humanity.[34]Matthew Vaughn was attached to direct the film but left in October 2012 to focus on the film Kingsman: The Secret Service.[35] Singer, who directed the first two X-Men films and produced X-Men: First Class, became the director of the film.[36] The screenplay was written by Kinberg.[37] Principal photography began in April 2013 in Montreal, Canada, and ended in August.[38] Additional filming took place in Montreal in November 2013 and February 2014.[39][40] The film was released on May 23, 2014.[41]
