In Trenga, we are told the story of Kate Nemo, a talented and fearless marine biologist. She is the grand-grand-grand-grand-grand-grandaughter of Captain Nemo and wants to find what really happened to his great-great-great-great-great-greatfather. To do so, she decides to explore the ocean in search of the Nautilus, the mythic submarine of the 20.000 Leagues Under Sea tale.

To begin her journey, she builts a submarine using techniques she learned with her grandfather studies: her submarine is a sustainable prototype able to travel in the deepest waters using a fuel system inspired in the breathing system of the starfishes.

When her first adventure begins, she is met by a colossal storm, sent to somewhere forgotten in the deepest reaches of the ocean. There she catches a glimpse of Nautlus running off even farther away and tries to follow it, but her submarine was damaged in the storm. Unable to keep going, she receives an unexpected visitor: a starfish that helps her to fix her submarine, as long as Kate helped her rescuing all the imprisoned starfishes. Afterwards, now ready for her journey and with a clear goal in mind, she follows the tracks left by the Nautilus, helping every sea creature she mets along the way. Those creatures become her friends and help her to conclude her mission.