Cell's Idea (セルの思いつき, Seru no Omoitsuki; lit. "Cell's Idea") is the three hundred eighty-eighth chapter of the Dragon Ball manga.
The cover depicts Cell, in his Perfect Form, holding up a finger.
Cell has just transformed into a Power Stressed form of his own, and calls Future Trunks an idiot for using a transformation that only gives brute strength. Trunks realizes this is why Vegeta never took on the Super Saiyan Third Grade form, and that Cell's right. Trunks reverts to his base form and tells Cell to kill him, since he has no chance now.
On an island far away, Krillin realizes that Trunks' ki has shrunk, but that Cell's is still huge. He quickly feeds Vegeta the Senzu Bean so they can get back to help. Meanwhile, Cell is about to kill Trunks for both him and Vegeta being such disappointments.
Up on The Lookout, Piccolo realizes just how powerful Perfect Cell is, and states that Trunks is about to die. However, Cell is impressed that Vegeta and Trunks had improved so significantly in a short amount of time, and asks if they had even more time, they could get even stronger. Trunks replies that he won't know until he tries. Cell then asks what Goku is doing, and Trunks answers that he's training to defeat Cell.
Cell is pleased by this answer, and announces that he plans to hold a tournament in ten days. He challenges Trunks to gather allies and get stronger so they can compete against him. Trunks is confused, wondering what Cell's goal is now. Cell states that it was formerly to kill Goku, but now it's just to have fun by causing utter terror for the world. Cell then flies away just as Krillin and Vegeta arrive.
Back on the Lookout, Bulma is yelling at Piccolo to go save Trunks, but Piccolo reveals that Trunks is all right. Piccolo, however, realizes that now he'll have to do some training of his own in the Hyperbolic Time Chamber.
Back on the Islands, Trunks has told Krillin and Vegeta about Cell's plans, which annoys Vegeta, thinking Cell is toying with them. However, Trunks and Vegeta are willing to train more for the tournament. At that moment, the damaged Android 16 arrives, wanting to compete in the tournament as well, but first asks to be taken to Capsule Corporation so he can get needed repairs. Trunks doesn't want the Android's help, but Krillin agrees to take the android, knowing they'll need all the help they can get against Cell, and that these androids aren't as bad as the ones from Trunks' future.
The next day would come the broadcast that would terrorize the world...