It's the semi-final of the painting competition hosted by Mariella Frostrup and the Rev. Richard Coles, and the five remaining amateur artists are facing their toughest challenge yet - capturing the human body in movement.With their place in the final at stake there is no room for any mistakes as they focus on their first challenge. For two hours a solo dancer spins, pliés and pivots in front of our artists, which they must try to accurately capture on canvas.With mentors Diana and Pascal on hand to help, all the painters are pushed out of their comfort zone. But that was just the warm-up act: for the main event a troupe of ballerinas appear and perform selected extracts from Swan Lake. Even the judges admit that this is a challenge that they wouldn't want to have to tackle!All five amateur artists step up to the plate and give it their best shot, with some stunning results, but only four of them can make it on to next week's final. Who will the public viewing panel choose to go straight through, and who will the judges send home?