Francine Stock hears from director Christopher Nolan about the tension between eco-conservatism and interplanetary pioneer spirit in his new space Blockbuster INTERSTELLAR. There's also the second part of a series featuring the sound effects experts - this time Randy Thom who added more than a little of himself to the spells and wand-craft of the Harry Potter series, and on the 30th anniversary of its release, Lord Puttnam talks about the enduring impact of THE KILLING FIELDS, particularly in Cambodia.