At first glance, it is a striking portrait by Edvard Munch, painted in 1892, a year before the Norwegian master was to create his most famous masterpiece, The Scream. But peer closely at the man’s sleeve along the bottom edge and two embracing, ethereal figures in a mysterious moonlit landscape are revealed. Detail of Lütken’s sleeve in the portrait. The intriguing painting within a painting by one of the most significant artists of the 20th century, a pioneer of expressionism, is to be seen for the first time in Britain after its rediscovery. It will be unveiled at the National