The story begins in March 1867, with a French narrator boarding the massive steamship 'Great Eastern' in Liverpool. Dubbed a "floating city," the ship boasts luxurious amenities and advanced engineering. The narrator reunites with his friend Fabian MacElwin and Captain Corsican, learning that Fabian's former love is aboard with her husband. As the voyage progresses, they interact with various passengers, and detailed descriptions of the ship's structure and operations highlight the maritime technological advancements of the era.