An explosion sends a tsunami towards the city of Atlantis. The Queen leaves Princess Kida behind and is lifted up into a floating crystal, which merges with the Queen and creates a protective dome over the city's innermost district, which sinks beneath the waves.
8,000 years later, in 1914, Milo Thatch, a Smithsonian Institution linguist who is ridiculed for his dream of finding Atlantis, is introduced by Helga Sinclair to eccentric millionaire Preston B. Whitmore, an old friend of Milo’s grandfather. Whitmore reveals that he made a bet with Milo’s grandfather to fund an expedition to Atlantis and gives Milo the Shepherd’s Journal, a book describing the history and path to Atlantis, offering him a place in the expedition. The expedition is headed by Commander Rourke and includes Helga; demolitions expert Vinny; geologist Molière; medical officer Dr. Sweet; mechanic Audrey; radio operator Mrs. Packard; chef Cookie; and dozens of soldiers. Their submarine Ulysses is attacked and destroyed by a mechanical leviathan guarding the entrance to Atlantis, leaving only a handful of survivors. Following the journal they travel through a dormant volcano and eventually arrive at Atlantis, where they are met by the still young Princess Kida.
