One day Moomintroll notices that something strange has happened in the Moomin Valley everything is grey; not just the sky and the river, but the trees, the ground, the Moominhouse, too! This is the way things tend to look like before the earth faces an awful fate coming from the skya comet! With the help of his father, Moominpappa, Moomintroll and his worried friends build the best raft ever and start on a challenging journey to the observatory. The wise professors there calculate that a ferocious comet will reach the Earth in four days, four hours, four minutes and 44 seconds. Maybe 4 seconds later. Its time to go back home as fast as they can! Will they get everybody back safe in time?