While being told tales from a crazy old fisherman, Jack is told about an underwater city that holds a time machine that could send him back to the past.
After finding the spot in the story where the fisherman last heard about the machine, Jack dives down to search underwater. While running out of air he finds a Jelly-Whale and gets swallowed into his jelly mass, providing oxygen for him to breath. While admiring the scenery he sees the city and calls for the whale to turn, and when accidentally stepping on a nerve, the whale complies, much like the pedals on a car.
When reaching the city, Jack meets up with the Triseraquins, a race of sea monkey-like people who are the keepers of the time machine. Their leader Guiness invites him to dinner to show their friendship. While Jack scarfs down the dinner of sushi, they each talk about their origin stories: how the Triceraquin's home is now under the sea, and how Jack came to be in their time. When asked why he came to their city, one Triceraquin blurts out about their time machine, to which Jack excitedly wants to see.
After dinner, Jack is showed the time machine and after a series of steps that seem legitimate, it turns out the time machine was really a bubble prison. It turns out that the Triceraquins planned for Jack to come to the city and be their prisoners so they could barter with Aku for their city to be on land again. After delivering Jack to Aku, Aku breaks a small hole in the Bubble prison to ensure a slow death for Jack. When asked about his side of the bargain, Aku shows his true colors and exclaims that he had "changed (his) mind!"
Feeling betrayed and guilty that they would have had Jack killed for nothing, the Triceraquins turn on Aku, sending troops in to stop him (while he shape-shifts from a spiked tube-worm, then a manta ray, and finally an octopus), to no avail. They instead, save Jack to make up for betraying him, where he then uses his magic sword to defeat Aku and have him retreat.
After a heart felt apology, and the truth about the time machine being a hoax coming out, the Triceraquins ask if there was any way to repay Jack. He gladly accepts a bag of sushi fish from the dinner prior for payment and heads off, in search of a way home.
- Casting by
- Collette Sunderman
- Many of the Triseraquins have UK-based accents that parody famous celebrities such as The Beatles, Alec Guinness, and Sean Connery.
- Goof: When Aku pokes the hole in the sphere that Jack is trapped in, his goatee is colored black.
- This is the only episode in the entire series that hints at Jack's real name.