Chris Dercon, director of Tate Modern, takes the helm of Artsnight for the fourth episode of the series. Chris asks why Berlin is the creative capital of Europe; the city is a magnet for artists and musicians, with an expanding array of galleries, museums and public arts intuitions. He talks to iconoclast Ai Weiwei, who has recently opened a studio in the city despite being unable to leave China. He explores the intriguing world of drone art and the pioneering work of the late Berlin-based artist Harun Farocki. He also commissions a new film about Nick Cave's formative years in West Berlin, when the city was burgeoning with creative talent prior to the fall of the Berlin Wall.

• Lily Cole
• Julie Walters
• Jessica Hynes