Little is known about why he fled across the border into the hermit kingdom, but securing his release will require some tactical diplomacy. Given the tense relationship between both countries, is Kim Jong Un prepared to come to the table? A look at research which suggests gold might not always be an effective hedge against inflation (08:52). And, why mountains stop growing (15:42).
For full access to print, digital and audio editions of The Economist, try a free 30-day digital subscription by going to www.economist.com/intelligenceoffer