In the early hours of Thursday 15 April 2010, British airspace began to be closed down due to a volcanic eruption in Iceland. What followed was unprecedented, with travellers stranded, aeroplanes grounded and millions of pounds at stake. But what is the truth about Iceland's volcanoes and how worried should we be in Scotland? Sally Magnusson goes to Iceland to reveal the truth about the country's volcanoes, separating the facts from the fiction. She uncovers the warnings that some feel were ignored about Iceland's volcanic ash and the danger it presents to everyone living in Scotland. She investigates the science behind volcanic ash and how safe it really is to fly. And finally she asks the question: if all this was caused by a relatively small volcano, what will happen when Iceland's larger volcano erupts?