What red lines need to be crossed before companies retreat from foreign markets? As political turmoil engulfs Turkey, total economic collapse threatens in Venezuela and other global threats emerge, In Business explores the point at which businesses decide that enough is enough. Does it depend on the size of the investment and do companies in different sectors play by different rules? And what reputational risk might companies suffer if they get that calculation wrong? Presenter, Matthew Gwyther, talks to business people who have stayed and those who have left. Did they see the red line clearly or would they make a different call second time around?