The film begins with the scene from Dragon Ball GT, episode 39: "Baby Put to Rest". Baby had escaped from New Planet Plant in his spaceship, but Super Saiyan 4 Goku powers up for a 10X Kamehameha and fires it towards Baby's ship, sending him into the sun and killing him.
The actual storyline begins then, propelling itself 100 years in the future where all the Z Fighters have died of natural causes except for Pan, who is more than 100 years old. She is shown being at the graveyard sitting on the burial site of her grandfather, Son Goku, paying her respects along with her grandson, Son Goku Jr., who was trying to catch a butterfly but then went to pay his respects for his great great grandfather, who departed from the Earth 100 years prior. Pan stands up and tells Goku Jr. that it is time to train, which he happily agrees with. She dreams of her grandson becoming a great warrior like her grandpa, but Goku Jr. is clearly not interested in training and always lets her down, rather it's flying, balancing or even catching a ball.
Goku Jr. studies in a local school where he is frequently bullied by Puck, a senior student who loves to fight. Pan, a very powerful person herself by a normal human's standard, wants to explore the potential of Goku Jr. But Goku Jr. being a non-violent person, always lets himself be bullied by Puck and his companions, thus underrating his abilities. One day, he lets Puck take his favorite pen which he calls Rocket Pen. Pan becomes extremely furious, and upset because of his behavior and yells at Goku Jr. for being so carefree, which causes her blood pressure to rise and she falls sick.
So she is admitted in a hospital by her grandson with the help of her neighbors, where he comes to know that his grandma's life was hanging by a thread which could snap anytime. So angry and disgusted with himself for being so care-free, which worsened the health of his Grandma, he runs out of the hospital to his house, pleading to God not to leave him alone and take his grandma away him. In the Japanese version, Goku Jr. pleas for someone to help his grandma.
When he returns home he feels a little nostalgic, as he recollects the past where he was constantly advised by Pan to be shrewd, stories of her past etc. At that point he comes to know about the magical Dragon Balls which would grant any wish. So, with the intention of healing Pan and for her speedy recovery, he starts his journey to his great great grandfather's cottage house at Mount Paozu.
On the way, he confronts Puck and his companions who start to bully him without knowing his sorrowful mood. But Goku Jr. was in no mood to be bullied and powers up generating a yellow aura around him. The actions were so clear that Puck and his friends left Goku Jr. alone.
After a long walk, Goku Jr. realizes that Mount Paozu is too far and would take forever to reach by foot. Luckily at that time a man driving an 18-wheeler stops and asks whether he wants a lift. Goku Jr. happily gets into the truck and they head off. The truck has a poster of a burger on the outside but is filled with garbage from the inside. Both Goku Jr. and the driver are hungry and the driver has nothing to eat. They stop at the Star Mark Service Stand. He tricks Goku Jr. by saying that Goku Jr. should go to the toilet before they head off. Once Goku Jr. is outside the truck he takes Goku Jr.'s food and leaves him stranded with only his empty bag.
At that time, Puck, who had been following Goku Jr., shows up and asks him if he wants some company as Mount Paozu was far away from their present location. He eventually advised Goku Jr. not to blindly trust anyone as their actual intentions could be hidden. He also told him that Mount Paozu was known as a haunted mountain filled with ghosts which are known to kill and eat humans. Then he asked Goku Jr. if he is going to run away like usual. But Goku Jr. declares that nothing is going to stop from going to Mount Paozu. At that moment Puck realizes that Goku Jr. can't go to Mount Paozu on a empty stomach, so he has an idea.
While Goku Jr. is waiting outside for wondering what Puck is doing in the store. It's reveal that Puck robbed the store by taking some food, and a cart. They use the cart so they can carry the food and ride on the road. After having some snacks they start climbing Mount Paozu. They pass through a dense forest and set up a camp there as it was getting very dark. During their supper, Puck comes to know that Pan is ill and is dying due to her illness. Goku Jr. explains to Puck that Mount Paozu has the magical Dragon Balls which have the ability to bring his grandma back to life. This changes Puck's heart and he returns the Rocket pen he stole from Goku Jr., which known to Puck was the cause of Pan's illness.
At that time, Puck sees eyes gleaming from the forest. They were surrounded by hungry wolves which immediately pounced on the duo. Goku Jr. and Puck used burning logs to threaten the wolves but in vain. compared to Puck, Goku Jr. was surrounded by so many wolves that seeing since he didn't have any option left, he jumped so high in the air out of fear that it was the only way to escape. Unknown to his own capability, he jumped so high that he reached the top of a very tall tree. With only Puck in grasp, all the wolves turned their attention towards him. When he was nearly going to be killed, a gun shot roared in the forest. A pretty girl with a shotgun showed up at the right time and chased away the wolves with her gun.
She took Puck and Goku Jr. to her house, and gave them a lot of food to eat. She leaves them so that they can enjoy the food uninterrupted, only to show her true color. She was a vampire sort of creature named Mamba and her sole intention was to eat them after being well fed. She then meets her pals Torga and Susha who are too interested in her catch. But, she is too resistant to let them have Puck as he is bulky.
After the supper, Goku Jr. and Puck go to the bedroom to have a nap. At that time, Goku Jr. tells Puck there is something fishy about the pretty girl who helped them. They arranged the beds to simulate their sleeping posture and quietly slipped away from the room. Just then, they saw Mamba entering the room and stabbing the bed with a huge knife. But, she instantly found that they were missing and went on a pursuit to get them. Goku Jr.'s guess turned out to be correct but he gave the credit to Puck who taught him not to trust strangers. When Mamba found them hiding on a window sill, they are chased by Mamba who in the end trapped them in a room where humans were cooked and eaten.
She caught Goku Jr. with her hair which she could use as a weapon and began to constrict his neck. Puck was trying to help him but just then she summoned a pick axe out of mid air, another one of her abilities. Goku Jr. falls unconscious due to the constant strangling, when she loosened up the hold thinking he has passed away. At that moment, he subconsciously hit Mamba with a ki blast which gave Puck some time to topple the huge vessel which had boiling salsa in it, thus trapping Mamba in it. Puck instantly cut off her hair and woke up Goku Jr. so they could flee away from the treacherous place.
They succeeded to give her a slip and came near a valley which was supported by a hanging bridge. Puck asked Goku Jr. to cross the bridge but he refused because of his fear of heights. Puck demonstrated that the bridge was safe by manually crossing the bridge and getting to the other side of the mountain which on perception gave Goku Jr. some confidence. He started to cross the bridge but saw below due to curiosity which pumped in his fear of heights to a whole new extreme. He was transfixed and the wind picked up, adding to his fear. Goku Jr. held the sideline ropes to steady himself, but the rope snapped, leaving him hanging on a single sliver of rope. Puck came on the bridge to rescue him, but when he was about to catch him, the whole bridge gave way leaving Puck nothing in grasp and he just fell down into the darkness of the valley. Goku Jr., after seeing this incident, overcame from his fear of heights and crawled up to the top of the mountain.
He constantly remembered the fun times he had with Puck during the journey and the sight of the Rocket Pen made him even more nostalgic. Just when he was on his way towards Mount Paozu, he saw a bear cub being chased by a demon who was reveal to be Susha who missed his meal because of his escape. The bear cub sought shelter near Goku Jr. to save himself. However, due to Goku Jr.'s fear of fights, he left the cub to its fate and began to run away from the demon. But, his scruples stopped him as he remembered the words of his grandma "Real strength, Having the courage to stand up for what's right." In the Japanese version, he regrets leaving the bear after he starts running away.
So he turned back and fought with Susha and defeated him effortlessly. He then began to nurse the injured cub but the mother bear, not having seen Goku Jr.'s heroic save, showed up and was about to attack Goku Jr. Just before any harm could be done the cub pacified the angry mother bear (father bear in English version) and interacted what actually happened. By knowing the fact the grateful bear asked Goku Jr. to climb on the back so Goku Jr.'s journey would be more peaceful. After a short time, they were at their destination, Goku's old house, but they again came in confrontation with Mamba, Susha, and Torga. Mamba was even more angry because of her butchered hair.
They began to chase Goku Jr. when a huge wild boar appeared in front of them and fired a cannon on Goku Jr. He introduced himself as Lord Yao and abused the trio for failing to catch even a boy. Yao who calls himself the King of the Demons. The trio apologized for their weakness and Yao began to attack Goku Jr. But the mother bear which was still accompanying him then came to rescue and started to put a lone fight against the demon lord. Unfortunately the mother bear was no match for the huge Lord Yao who defeated her effortlessly. Yao then grabbed the bear in a stranglehold and was crushing it to death when the shrieks and yells of the bear filled Goku Jr. with extreme emotions that transformed him into a Super Saiyan.
The whole outlook of Goku Jr. changed due to this and the usually timid fellow began to wage a lone fight against the seemingly invincible Lord Yao. He instantly took an upper hand and began to pound Yao to a point when he fell defeated and unconscious (or possibly dead). After the fight, even Goku Jr. fell unconscious as his body was not trained enough to handle the power of Super Saiyan. After that, when he regained consciousness he was unable to recollect his fight with Lord Yao suggesting he wasn't even mentally trained for going Super Saiyan. In the Japanese version and English version, Goku Jr. thought that It was the mother bear who defeated Lord Yao.
In the end, he found Goku's residence and began to search for the Dragon Ball. After a short search, he got the 4 star ball. He came outside and began to wish the dragon for his grandma's recovery and Puck's revival. Nothing happened. After repeatedly pleading Shenron and Kami in the Japanese version. Goku Jr. lost his temper and threw the ball away, which landed near Goku himself. Goku appear in front of his descendant and explained to Goku Jr. that he has to collect all seven Dragon Balls for his wish to come true. He introduced himself as his great great grandfather, although he did have trouble trying to figure out exactly how many greats it is, and told him to just call him Grandpa Goku. Goku then told his grandson of how proud of him he was for his bravery.
Just then a helicopter hovered above them, out of which Puck and Pan called Goku Jr. Not surprisingly, Goku vanished after this and wished his grandson good luck for his future, and explained him that his willingness to save his grandma and friend actually saved them all. Goku then bids farewell to his grandson, by addressing him by his full name, and Goku Jr. happily agrees now that he has the Four-Star Ball in his hand. Goku Jr. then joined Pan and Puck in the helicopter. In the Japanese Version, as he leaves, Goku Jr. told Goku that he'll keep hanging in there, and told Goku just to watch. In the English version, Goku Jr. bids farewell to Goku, and Goku tells him to keep the Four Star Dragon Ball as a memento of him, just like how he did when was his grandson's age. Goku then happily says goodbye to his grandson one last time. Goku Jr. also says farewell to his grandfater while, he, Pan and Puck departed happily from Mount Paozu back to Satan City. The movie ends with an Image of Goku in the sky.
- Masako Nozawa as Son Goku Jr. & Son Goku
- Yuko Minaguchi as Pan
- Toru Furuya as Puck
- Miki Ito as Mamba
- Shin Aomori as Getto (known as Susha in the U.S)
- Kazuyuki Sogabe as Rakkaru (known as Torga in the U.S)
- Ryuzaburo Otomo as Yomao (known as Lord Yao in the U.S)
- Joji Yanami as the Narrator
- Stephanie Nadolny as Goku Jr.
- Elise Baughman as Pan
- Adrian Cook as Puck
- Sean Schemmel as Goku
- Amber Cotton as Mamba
- Peter Mayhew as Susha
- Christopher Sabat as Torga
- Brice Armstrong as Lord Yao
- Andrew Chandler as the Narrator
- Goku jJr. goes by two nicknames in the film, Goku by Puck and Son Goku by Goku himself. However in the English version, Goku only calls Goku Jr. "grandson", while Puck still calls Goku Jr "Goku".
- When Goku Jr. hitches a ride with the trucker, the truck promotes a type of burger called "Moo Macs" and there is a logo similar to the McDonald's golden arch. The burger obviously meant to be a parody of the McDonald's Big Mac burger.
- Coincidentally, McDonald's was now one of the sponsors for Dragon Ball Kai in the 2000s.
- When Goku Jr.'s rucksack is emptied by the truck driver, it appears to contain snacks similar to Pringles, even sharing the same logo on the pack.
- Even though Pan is the only of the original Z Fighters still living, the Dragon Balls are not turned to stone, which means that Dende or a new Guardian of Earth must be there as well.
- This is the first appearance of Goku Jr., he will not appear again until the final episode of GT where he wears his great-great grandfather's Gi instead of his own Gi.
- When Goku Jr.'s rucksack is emptied by the truck driver, it appears to contain snacks similar to Pringles, even sharing the same logo on the pack.
- This is also the first appearance of a Taunt in a film since Bio-Broly.
- It is never explained how Puck was saved by Pan, including how he survived from falling into the deep gorge. Along with how Pan recovered enough to be able to ride in a helicopter, or how she knew Goku Jr. was on a journey to the mountain, although she may have simply tracked them both using ki sense.
- Goku Jr., along with Mamba, Susha, Torga and Lord Yao made their video game debut in Dragon Ball Z Dokkan Battle.
all information on Dragon Ball GT TV Special came from http://dragonball.wikia.com/wiki/Dragon_Ball_GT:_A_Hero%27s_Legacy