In 1915, Don Juan, Elizabeth, their German Shepherd Smile, and their pet mice Top Connors and Ronnie, are tasked by the U.S. Navy to explore the ocean depths in search for the wreck of the Titanic.

A gang of tiger sharks led by Mr. Ice orders them to cut the cable of the bathysphere that the humans and their pets are on and sink it, because he dislikes the craft’s yellow color.

During a battle between the merpeople and sharks, a young toy soldier is promoted to be the new general of a 19th century-style artillery group after being at first mistaken for a little girl on account of a wig he wore.

After consuming one drip of the flask, the elder is tied to a couple of bricks and dropped into a deep well of water which almost drowns him, as a few of the mice jump in to save him, realizing that the elixir was illegitimate.

The king then transports the Titanic and the expeditioners to the bay of a secret island, where Don Juan and Elizabeth will live happily ever after, while being able to return to Atlantis whenever they wish.