Published in 1877, Off on a Comet starts with a comet called Gallia, that touches the Earth in its flight and collects a few small chunks of it. The disaster occurs on January 1 of the year 188x in the area around Gibraltar. On the territory that is carried away by the comet there remain a total of thirty-six people of French, English, Spanish and Russian nationality. These people do not realize at first what has happened, and consider the collision an earthquake.