What do we want from the movies we see? Judging from the global box office returns the answer is escapism, superheroes and awesome special effects. But that's not how all A-list Hollywood directors make their name. HARDtalk speaks to Paul Greengrass who makes taut, tense films that aren't always easy to watch. His biggest hits were the Bourne movies starring Matt Damon, his most intense film was probably United 93, based on the events of 9/11, and his new release is about Somali pirates. How does he juggle truth, art and entertainment?