Theodore Tugboat finds Atlantis: The Lost Empire

Theodore Tugboat finds Atlantis: The Lost Empire is second upcoming Theodore Tugboat crossover and the second Thomas & Friends/MLP:FIM spin-off to be made by Hiatt Grey.

Plot
The film begins with a large tidal wave, triggered by a distant explosion, which threatens to drown the island of Atlantis. In the midst of an evacuation from the capital city, the Queen of Atlantis is caught by a strange, hypnotic blue light and lifted up into the "Heart of Atlantis", a powerful crystal protecting the city. The crystal consumes her and creates a dome barrier that protects the city's innermost district. She leaves behind a young daughter, Princess Kida (Cree Summer), as the island sinks beneath the ocean.

Several thousand years later, in 1914, Milo Thatch (Michael J. Fox)—a cartographer and linguist at the Smithsonian Institution who is marginalized for his research on Atlantis—believes that he has found The Shepherd's Journal, an ancient manuscript allegedly containing directions to the lost island. After his proposal to search for the Journal is rejected by the museum board, a mysterious woman, Helga Sinclair (Claudia Christian), introduces Milo to Preston B. Whitmore (John Mahoney), an eccentric millionaire. Whitmore has already funded a successful effort to retrieve the Journal as repayment of a debt to Milo's grandfather and recruits Milo to lead an expedition to Atlantis as soon as he deciphers it.

The expedition departs with a team of specialists led by Commander Rourke (James Garner), who also led the Journal recovery expedition. The crew includes Vinny (Don Novello), a demolitions expert; Mole (Corey Burton), a geologist; Dr. Sweet (Phil Morris), a medical officer; Audrey (Jacqueline Obradors), a mechanic; Mrs. Packard (Florence Stanley), a radio operator; and Cookie (Jim Varney), a mess cook. They set out in the Ulysses, a massive submarine, but are soon attacked by the monstrous Leviathan, a robotic lobster-like creature that guards Atlantis' entrance. The Ulysses is destroyed but Milo, Rourke, and part of the crew escape and make their way to a cavern, described in the Journalas the entrance to Atlantis.

After traveling through a network of caves and a dormant volcano, the team reaches Atlantis. They are greeted by Kida—who, despite her age, resembles a young woman—and discover that the Atlantean language is the basis of many existing languages (which allows the Atlanteans to understand English). Kida enlists Milo's aid in deciphering the Atlantean written language, long forgotten by the natives. By swimming deep within the city's submerged ruins and translating underwater murals, Milo helps Kida uncover the nature of the Heart of Atlantis: it supplies the Atlanteans with power and longevity through the crystals worn around their necks. He is surprised this is not mentioned in the Journal, but upon examination realizes a page is missing.

Returning to the surface with Kida, Milo discovers Rourke has the missing page. Rourke and the crew betray Milo, intending to bring the crystal to the surface and sell it. Rourke mortally wounds the King of Atlantis (Leonard Nimoy) while trying to extract information about the crystal's location, but finds its location for himself hidden beneath the King's throne room. The crystal detects a threat and merges with Kida. Rourke and the mercenaries lock Kida in a crate and prepare to leave the city, knowing that when the crystal is gone the Atlanteans will die. Milo berates his friends for betraying their consciences and ultimately convinces them to leave Rourke and remain in Atlantis. The King explains to Milo that the crystal has developed a consciousness; it will find a royal host when Atlantis is in danger. As he dies he gives his crystal to Milo, telling him to save Atlantis and Kida. Encouraged by Sweet, Milo rallies the crew and the Atlanteans to stop Rourke.

In a battle inside the volcano, Helga and the other mercenaries are defeated, including Rourke, killed when Milo slashes his arm with a crystal shard. As Milo and the others fly the crystal back to the city, the volcano erupts. With lava flowing towards the city, Kida (in her crystal form) rises into the air and creates a protective shield. The lava breaks away harmlessly, showing a restored Atlantis, and the crystal returns Kida to Milo. The surviving crew members return to the surface and promise to keep the discovery of Atlantis a secret. Milo, in love with Kida, stays behind to help her rebuild the lost empire.

Trivia

 * Belldandy, Keiichi Morisato, Urd, and Skuld guest star in this film.
 * Oliver the Vast will work for Commander Rourke in this film.