Two children - Conrad and his little sister, Sanna - set out from their village high up in the Alps to visit their grandparents in the neighboring valley. It is the day before Christmas but the weather is mild, though of course night falls early in December and the children are warned not to linger. The grandparents welcome the children with presents and pack them off with kisses. Then snow begins to fall, ever more thickly and steadily. Undaunted, the children press on, only to take a wrong turn. The snow rises higher and higher, time passes: it is deep night when the sky clears and Conrad and Sanna discover themselves out on a glacier, terrifying and beautiful, the heart of the void.