The narrative begins on the coast of Algeria where Captain Hector Servadac and Count Wassili Timascheff are on the verge of a duel over a lady when a cataclysmic convulsion of nature strikes the earth. A comet grazes the planet, picking up a fragment of Algerian soil along with its inhabitants, air, and water, and carries them off into interplanetary space. Servadac and his orderly Ben Zoof soon discover that the laws of gravity have been altered, the days are now six hours long, and the sun rises in the east. They embark on an extensive exploration of their new world, which they name Gallia, and find themselves completely isolated on a small island.
As the comet swings into its orbit, they encounter extreme temperature shifts and near-collisions with Venus and Mars. Later, they set sail on the yacht Dobryna to search for the rest of humanity, discovering that the Mediterranean and Europe have been submerged and replaced by an arid, metallic landscape. During their voyage they meet other isolated survivors, including some stubborn British officers at Gibraltar and a miserly German Jewish merchant named Isaac Hakkabut, who refuses to share his cargo.
They also pick up mysterious messages in bottles and via carrier pigeons regarding Gallia's trajectory. Eventually, as the asteroid recedes from the sun and extreme cold sets in, the voyagers take refuge in a volcanic cave which they name Nina's Hive. They spend the dark winter months surviving the freezing temperatures on the solid ice-covered Gallian Sea while planning further rescue missions across the frozen expanse.
