Greenland, the largest island in the world, is unlike any other country. The film recounts the exploration of the Inlandis cavities in Greenland during the summer of 1992. Janot Lamberton, one of the pioneers of these expeditions, ventured, with speleologists and mountaineers, into the moulins, these immense crevasses that tear through the back of the Inlandis, a vast glacier four times the size of France, while glaciologist Louis Reynaut studies infraglacial phenomena. It is obviously not easy to penetrate the depths of the ice and film at a depth of 150 meters in sub-zero temperatures. The light is blue in one of the most fascinating landscapes on the planet, where scientists and explorers collaborate to deepen their knowledge of the Earth.