Autumn invades the Mumin Valley and those who go there to visit the Mumin family find it very changed, very different from what they had imagined. Also, the Mumin family is not at home. All those who have gathered in the empty dwelling will have to make an effort so that the coexistence is good. Among them are the Filifjonka and the Hemul, the Mymla, the Onkelskrutt and the little homsa Toft. And the Snusmumrik, which goes a long way until reaching the valley, where it has lost a very important thing ... In the garden, the blue crystal ball continues on its pedestal, reflecting great changes as the darkness looms ever closer to your surroundings. But one night, in the center of the ball, a tiny speck of light finally appears, shining firmly.