This TV Movie tells the story of "Future" Trunks; that is, the Trunks from the alternate future where Goku has died and Androids terrorize the Earth. Amongst other things, it shows how Gohan trained Trunks, their fights with the Androids, and what inspired Trunks to go time traveling.
Dragon Ball Z: The History of Trunks
In a dark future where the Androids have taken over Earth, Gohan and his student Trunks are the last defense against these deadly killing machines.
