Children disobey their parents all the time. But rarely have the consequences of a clandestine fishing trip been as grave or exciting as in this grandly scaled tale, where three adventurous children unwillingly become denizens of the sea - and must race against time to reclaim their lives as human beings.

The impulsive and optimistic Fly, his cute baby sister Stella and their stout but intelligent cousin Chuck are being looked after by Chuck's mother, Aunt Anna, while Fly and Stella's parents are out. Fly can think of nothing worse than an evening with his bossy Aunt and as Anna concentrates on putting Stella to sleep and Chuck does scientific calculations on his laptop, Fly gets more and more bored. But, the fairytale, which should have put Stella to sleep, puts Anna to sleep instead. Fly recognises an opportunity and bullies Chuck into joining him. And so off the children go on a fishing trip to the beach.

By the time they decide to go home the tide has entrapped them on a small island, cutting them off from the shore. Chuck is particularly alarmed, and his panic grows when Fly and Stella disappear. Moments later he finds them, by falling through a concealed opening in the rock. They are in a subterranean passage that seems to go towards the shore, but instead of finding the shore they literally stumble over the entrance to the enigmatic professor MacKrills cave - a mixture of Maritime museum and marine-biology Lab

Here they are frightened, but the lonely professor welcomes his young visitors with open arms and enthusiastically explains his latest invention to the fascinated children. The professor believes that global heating will eventually melt the ice cap and make the seas rise to cover all land. But his new 'fish potion' can save humanity by transforming human beings into fish. To explain the formula for making this potion, the Professor sings a rhyme he has made to assist his memory and this very quickly becomes an elaborate song-and-dance act.

The professor proposes to demonstrate the effectiveness of his potion by drinking it. While he is setting up a video camera to film his own transformation into a fish, the thirsty Stella confuses the potion with lemonade and drinks some of it. She staggers about, knocks over the camera and falls against cables as her shape begins to blur. Before finally collapsing she manages to short the electricity and plunge the whole house into darkness.

Fly and Chuck find out that Stella is missing, and while Chuck discovers that her transformation has been filmed by the video camera, Fly finds an almost suffocated starfish, dressed like a doll. He kindly tries to 'save' her by dropping her into the sea, mistaking it for one of the professor's experiments. Chuck calls out to stop him but a second too late. Stella is now a fish forever - unless the two cousins can get the antidote to her within 48 hours.

With a bottle of fish potion and antidote, Fly, Chuck and the professor sail out to search for Stella in a little rowing boat on the stormy sea, but to no avail. Desperate to find his sister before the 48 hours are up, Fly drinks some of the fish potion, jumps into the water and transforms into a fish.

Chuck and the professor are washed overboard by a huge wave, and Chuck, who can't swim, also drinks some of the fish potion to avoid drowning and turns into a jellyfish. The bottle of antidote sinks to the bottom of the sea, leaking its contents, which proves to have the adverse effect of the fish potion, giving fish human abilities to think and speak.

Some of the antidote is ingested by a shark and his pilot-fish companion, who immediately develops human powers, like thinking and speaking. The pilot fish, however, being much smaller than the shark, gets a proportionally much larger dose and develops more intelligence. The shark remains comparatively stupid.

Back in the house, Aunt Anna has woken up and realised that the children are missing. When Fly and Stella's parents arrive home, she is in a panic, and a serious search for the children begins. Fly's missing fishing rod starts them off on the right track, and they head for the beach.

At the bottom of the sea, Fly finds his missing sister, and together they marvel at the spectacular surroundings. They meet all kinds of incredible fish-creatures, and Stella in particular becomes friends with a small sea horse. They are also reunited with their cousin Chuck, but when he tells them about the loss of the antidote and that they will be all fish forever if they don't find it within the 48 hours, the situation becomes serious. Together, they set out to solve their problem.

In the meantime, Joe the pilot fish has realised that the antidote can bring him unlimited power. He has already fed tiny doses of it to thousands of fish, giving them limited speaking and thinking abilities and turning them into his private army, which is commanded by the less intelligent shark. Joe sets up headquarters in the great sunken ocean-liner, the HMS ATLANTIC, speaking to his new underlings of the glorious 'New Era' awaiting them all under his leadership.

The three friends have followed him to try to reclaim the antidote but they are caught, and when they refuse to tell Joe how he can make more antidote, they are imprisoned.

Stella's friend the seahorse, rescues them all. But they still haven't got the antidote until Fly recalls the song the professor had made to remember the ingredients of the antidote. And all the ingredients can be found in the sea! They start collecting. but the 48 hours are running out, and Joe and his army are closing in!

Professor MacKrill has survived the boat ride and returned home, where the children's concerned parents await him. After a thorough scolding, mostly from Aunt Anna, they join forces launching the professor's vacuuming vessel with which they can search the bottom of the sea for their children.

At the bottom, the three friends' situation has become critical. Joe and his army have surrounded them, their newly acquired antidote has been taken from them, and Fly is injured in battle. But at the last moment, the professor's vacuum vessel sucks the entire army away!

Counting the last minute of the 48 hours, Chuck sees one final chance. His ingenious plan gets them all into the professor's laboratory through the pipe system supplying seawater to the professor's house. Inside, they reach the lab. But the villain Joe has followed them - and manages to steal the last bottle of antidote for his own evil purposes while they are counting the seconds before their transformation into fish becomes irreversible!

Fly chases the villain and defeats him in a final show down, cleverly turning Joe's ambitions against him. Chuck returns with the antidote, and he and Stella regain their human form just in the nick of time. But what became of Fly? For a few moments, it looks like he has suffered a horrible death under the feet of Aunt Anna's stiletto heal before he could recover from his fish-shape but all ends well, and the children are happily reunited with their parents.

Only Stella is sad, missing her seahorse friend. But the professor still has a trick up his sleeve.

Character Descriptions

FLY

Fly is 13 and always has a snappy remark handy and is extremely self sufficient. He is an optimistic boy that never wastes time worrying. He is full of good intentions but often manages to upset the surroundings with impulsive, spontaneous behaviour. However, he usually manages to get out of trouble.
With his optimistic and brave attitude he is a likeable boy. Fly hates being stuck with his boring cousin, who never wants to join in the mischief.

However, during the story, Fly learns to appreciate his cousin's abilities and realises the necessity of thinking before acting, if only once in a while.

CHUCK

Chuck is Fly and Stella's cousin and is an introvert, a nerd and a loner, who would rather use his time to study genes and DNA molecules, than spending time with his peers. Chuck dislikes visiting his irritating and mocking cousin Fly, with whom he has nothing in common. He is an only child and was brought up by his mother, Anna, in a stern and overprotective yet loving manner. He always does what mommy says he should and thinks before he acts and is therefore relatively devoid of initiative on all levels, except the one concerning expansion of his intellectual horizon.

Throughout the story, Chuck is forced to take responsibility and act on his own initiative to save himself and his two friends. That is the breaking point for Chuck personally, but also his friendship with Fly.

STELLA

Fly's little sister is a happy, little girl, straightforward and curious like most children her age. Stella is very close to her big brother, just like he is very protective of her. During the story, Stella is transformed into a little star fish and with the open-mindedness of a child; she easily adjusts to the new circumstances in the underwater world.

PROFESSOR MAC KRILL

The professor is, as most highly intelligent people, a bit confused and absent-minded. He has lived most of his life secluded from the rest of the world and has therefore forgotten how to socialise or even how to have an ordinary conversation.

Apart from being enthusiastic and devoted to his work, he is a really nice guy. He wants to like people but he doesn't understand them. This makes him lonely at times, but whenever somebody shows genuine interest in his work, he gets all fired up and can talk forever.

JOE

Joe, until he was transformed, spent his life as a fish by cleaning the sharks teeth. When the two are transformed they exchange roles. Both of them do acquire intelligence, but Joe gets considerably more than the shark. Joe realises immediately that he now has the position of power in the relationship.

A personality blend of TV evangelist, serial killer and demagogue makes him - with the shark as his faithful underling - into the villain of the film, driven by an insatiable thirst for power.

He is calculating, egotistic, manipulative and intelligent.

His character develops gradually throughout the film, at the start, he is charming and humerous but the more of the anti-fish potion he drinks he gradually becomes psychopathic and menacing,

THE SHARK

Joe's henchman, the shark is stupid but dangerous. Badly treated by Joe, he does not have the brain's to rebel and simply continues to carry out his orders, occasionally feeling rather hard done by.