Neil MacGregor examines the emergency money - Notgeld - created during World War One and its aftermath. Small denomination coins began to disappear because their metal was worth more than their face value. People hoarded them or melted them down. Paper notes replaced coins, but as cities produced their own money, there was also currency made from porcelain, linen, silk, leather, wood, coal, cotton and playing cards. He also focuses on the crisis of hyperinflation in the early 1920s. At its peak, prices doubled every three and a half days, and in 1923 a 500 million mark note might buy a loaf of bread. Producer Paul Kobrak.