Dragon Ball Z: The History of Trunks - Plot

Plot

Goku dies from a viral heart disease, and six months later, the Z-Fighters, except Gohan, are killed by Android #17 and Android #18. With the death of Piccolo, Kami dies as well and the Dragon Balls are rendered permanently useless, leaving it impossible for the Z Fighters to be revived.

Thirteen years later, Gohan, now a Super Saiyan, repeatedly tries to challenge the androids but they are too strong. He begins training Vegeta and Bulma's 14-year-old son, Trunks, who is eager to defend the Earth. Gohan attempts to provoke Trunks enough to trigger his transformation into a Super Saiyan. Several times, Trunks comes close, but lacks enough motivation to maintain the form.

The androids attack an amusement park. Gohan transforms and battles them but is being overwhelmed. Trunks comes to his aid and fights Android #18 but is easily defeated. Gohan saves him and they hide in some debris. Unable to find their targets the androids bomb the entire area and leave. Trunks and Gohan survive although Gohan loses his left arm. They go home where he recovers and then resumes Trunks' training.

Just as the training is finished a huge explosion hits the city. Gohan pretends to agree to allow Trunks to join him in the battle, then knocks him unconscious and goes alone. Gohan unknowingly increases his power to become an Ascended Super Saiyan and puts up a very good fight against the androids, but his lost arm proves to be a major disadvantage and he is eventually killed. Trunks awakens after sensing Gohan's energy signal vanish, and hurries to the city to find Gohan's body laying face down in a puddle of water. As he goes towards Gohan, he mutters to himself about Gohan and why he left, and etc. Trunks is enraged at the death of his best friend and finally undergoes his transformation into a Super Saiyan.

Three years later, Trunks and Bulma are working on a time machine when a warning sounds, indicating that androids are nearby. Trunks confronts them but is badly beaten and left for dead. He awakens in his house with his mother at his side, and finally decides they must use the time machine to deliver the medicine needed to cure Goku's heart disease years ago by giving it to Goku himself, hoping that this will prevent Goku's death and prevent their future from happening.

Trunks departs for the past in the time machine as the credits roll, showing scenes of Trunks' battle with Mecha-Frieza, his encounter with Goku and the Z Fighters, and the awakening of Androids 17 and 18.