"The Terrifying Message" (恐怖のメッセージ Kyōfu no Messeiji, lit. "A Message of Terror") is the three hundred thirty-fifth chapter of the Dragon Ball manga.
Although Goku says that he cannot see Vegeta as a father, he admits that Future Trunks does resemble Vegeta. Future Trunks tells Goku that he will be born in two and a half years, but that he has come to discuss more serious business. He informs Goku that in three years, on May 12, a pair of powerful monsters will appear on an island near South City. Goku, considering his most recent battles, asks if they're aliens. Trunks says that the duo are really cyborgs created by Dr. Gero, the chief scientist for the Red Ribbon Army - the now defunct organization Goku defeated more than a decade ago as a child. Goku, shocked to learn that they have resurfaced, asks if they (Gero specifically) are attempting world conquest again. Future Trunks says that he's not sure but believes so. He then says that the two cyborgs, called "Mechanical Men Nos. 19 & 20," killed Dr. Gero. Goku is surprised that someone who defeated Frieza so easily could be frightened, realizing that these cyborgs are stronger than the tyrant himself. He asks if the others could help, but Future Trunks informs Goku that he is the only Z Fighter left on Earth in his time.
Future Trunks proceeds to tell Goku that all of the other Z Fighters except for Gohan will be killed shortly after the cyborgs appear. He says that Gohan was the one who trained him, but that even he will perish at the cyborgs' hands. He also tells him that when Piccolo dies, the Dragon Balls will disappear forever as nobody can be revived again. Goku asks what will happen to him and also asks if he got killed by the androids too, and Future Trunks tells him that he never got killed by the androids, but he will die of a heart virus before the androids appear. Goku says that he is disappointed that he will not get to fight the cyborgs, which shocks Future Trunks. He tells Goku that he is a true Super Saiyan just like his mother told him, and then gives Goku the Heart Medicine, telling him that there is a cure in his time, but tells him to keep it safe with him as there isn't a cure in this era. Goku is overjoyed, and Future Trunks tells him that he has faith in him to fix things, and that his mother worked on the time machine so that Goku could help.
Goku, upon hearing that Future Trunks' mother knows him and made the time machine, quickly deduces that it must be Bulma. Goku is stunned, and Future Trunks explains that Yamcha was unfaithful to Bulma, which led to their breakup and Bulma falling in love with Vegeta. He also says that his parents never married, and that this is the first time he has gotten to see his father. He makes Goku promise not to reveal his parentage, lest it jeopardize his existence. Future Trunks decides to return to the future to reassure his mother. Goku asks if they will meet again. Future Trunks says that it takes a while to build up power in the time machine, but that he will return to fight with them if he is still alive. Goku promises to train hard and Future Trunks flies off. Goku is unsure how to deliver the news to the rest of the Z Fighters, but is relieved of having to do so due to Piccolo's exceptional hearing. Piccolo tells the group everything except for Future Trunks' parentage. Yamcha and Bulma seem skeptical of the story, but Piccolo says that he will train. Just then, Future Trunks' time machine rises into the air and then disappears. This convinces Krillin, Tien Shinhan, and Vegeta of the story's credibility, and they decide to train for the battle.