The Z Warriors move Goku to Master Roshi's house for fear that the Androids might try to kill Goku. Bulma contacts the Z Warriors and tells them that she saw a time machine like Trunks's. Trunks and Gohan fly out to look at the machine and find an egg shell nearby. In a town near them, a monster is absorbing people left and right. Piccolo, fearing that he will never be strong enough to stop the Androids, decides to fuse back with Kame. When Piccolo arrives, Kame tells him about the horrible creature attacking Gingertown. The two fuse with Piccolo as the base, and the two become one again. Piccolo flies to Ginger town to face this new threat. He encounters a horrible creature and the two fight. Cell holds Piccolo captive and absorbs an arm. Piccolo breaks free and demands to know more about his opponent before he loses his life to it. Cell agrees to Piccolo's last wish. The monster says it is called Cell, another one of Dr. Gero's creations. When Trunks returned to the future and killed Androids 17 and 18 of that time, Cell killed Trunks and stole his time machine to return to the past where the Androids were still alive. Cell reveals about how Dr. Gero abandoned the project on him but left the computer on to develop him on its own. In order to reach perfect form, he needed the beings of two figures crucial to the powerup - Androids 17 and 18. As newly hatched, he needed energy. That is why he has been absorbing people. Piccolo swears that he will not allow Cell to reach his perfect form. Then, he tears off his useless limb and regenerates his arm. The two fight again, but Cell runs off and evades Piccolo as it gathers more energy. Piccolo and the other give chase after the new menace.
The Androids head for Goku's house, terrorizing everyone in their path, and find he is not there. They then head for Master Roshi's house, still viewing the whole thing as a game. Gokou recovers from his illness and, hearing everything while asleep, prepares to join in fighting. Goku goes to Gohan and then to Vegeta and Trunks to tell them all of a place where you can train for the equivalent of a year but in only one day. All of them go to Kame's Lookout to enter the Room of Spirit and Time. Only two people can enter the room at a time however, so Vegeta and Trunks go in first. Meanwhile, Cell has gained enough strength to finally go looking for the Androids to achieve his perfect form. The Androids reach Roshi's house and Piccolo leads them to a nearby island to fight. As the two fight, Cell shows up on their island battleground. Cell easily beats Piccolo and heads for Android 17. Android 17 knows nothing about Cell and thinks of him as just another unworthy opponent, but Cell also easily beats the Number 17. Before Cell is able to absorb Android 17, Android 16 joins the fight. Android 16 overwhelms Cell. Cell becomes buried in a pile of rubble, but emerges atop Android 17 and absorbs him. Cell changes into form 2 and easily beats Number 16 with his newfound strength. Then, he heads for Android 18 and devours her, reaching Perfect Form. The Saiyans finish their training in the room of Spirit and Time, and Bulma rebuilds Android 16, who joins the Z Warriors.
Cell, in his infinite arrogance, announces the Cell Game, a tournament to give people the chance to fight him, one on one. If Cell survives, he will destroy the Earth. Goku and Cell battle to a standstill. Goku suddenly stops fighting and says that he will let Gohan take his place. Goku even gives Cell a Senzu Bean to keep things even! Gohan says that Goku is making him fight because when he gets angry his power rises unbelievably. Cell wants to see Gohan's hidden power, so he begins to beat Gohan mercilessly to force him to get angry. But no matter what Gohan never gets angry enough to fight back. Goku watches patiently and keeps anyone else out of the fight. Android sneaks up on Cell since the androids cant power up. Number 16 puts Cell in an arm lock and tells everyone to clear out so he can activate the Self Destruct mechanism that Dr. Gero put inside all his Androids. But Krillin yells to him that Bulma removed it when she put him back together. Cell laughs at 16's ignorance and destroys him again.
Cell gets tired of waiting for Gohan to get angry and threatens to kill the spectators. Cell flies to Krillin to steal his bag of Senzu Beans and heads back to Gohan. Cell creates 7 little clones, the Cell Jr's, to battle the spectators. Gohan watches helplessly as the Cell Jr's attack his friends. In the background, Mr. Satan and a camera crew had been documenting the tournament. Number 16's head lands near Mr. Satan and demands to be taken near Gohan so that he can tell Gohan how to save the world. After much reluctance, Mr. Satan slowly walks out intot he ring and throws the head toward Gohan, then slinks back behind a rock like the coward he truely is. Android 16's head encourages Gohan to fight, until Cell finally noticing the exchange between the two, crushes the head of Android 16. This sends Gohan into a rage and he powers up to SSJ2. Gohan steals the Senzu Beans back from Cell and easily beats the Cell Jr's. Gohan beats on Cell for awhile, forcing the enemy to power up to 100%. Cell can still not beat Gohan. Gohan lands a tough kick to the body of Cell forcing Android 18 back out, and forcing Cell to degrade to his 2nd form. Seeing no way to win in an even weaker form, Cell activates his self-destruct sequence. To save the Earth, Goku teleports Cell to King Kai's planet. Cell explodes and King Kai's tiny planet is destroyed. Goku, King Kai, Bubbles, and Gregory die in the blast.
The Z Warriors are all standing around in disbelief, when a fireball out of nowhere flies through Trunks's body. The heros look up to find Cell, in his perfect form, smiling down on them. Here we go again!
Cell explains that when he exploded, a single brain cell remained, from which he rebuilt himself. And due to his Saiyan DNA, the beast was able to come back stronger than before, in his perfect form. Vegeta gets mad and fires multiple blasts at Cell, but Cell stands by unharmed. Cell knocks Vegeta out and fires a shot at his helpless body. Gohan however zips over to Vegeta and takes the blast for him, rising battered and bloody. Cell and Gohan begin a Kamehameha duel, but it comes to a stalemate. Through King Kai, Goku yells encouragement his son. The remaining Z Warriors (Yamcha, Tien, Krillin, and Piccolo) fire all they have at Cell, but to no avail. Vegeta wakes back up and gets angry at the show of force from these low class Saiyans, Gohan and Goku. He fires a blast borne of hatred at Cell and it is powerful enough to distract the mighty creature. Goku yells to Gohan that this is his chance to finish Cell for good. Gohan puts all he has into his Kamehameha, and disintegrates Cell.
The Z Warriors head victoriously to Kame's Lookout, and Vegeta flies away, disbelieving that Gohan could be stronger than he. Mr. Satan and the news reporters wake up, and Mr. Satan, seeing the empty battlefield, takes all the credit for Cell's destruction. As the world celebrates Mr. Satan, the Z Warriors rest in Kame's Lookout, with Dende (the new Kame) who heals Gohan and Trunks. Android 18 awakens after the battle and the Z Warriors prepare for another battle. Krillin stops them from killing her and she flies away to the background of the Warriors joking on how Krillin has a crush on her. The Z Warriors gather the Dragon Balls and prepare to make their wishes. First they wish to remove all the bombs from inside the Androids. Then they wish to bring back all those killed by Cell. Goku however cannot be brought back, but he tells everyone through King Kai that it's ok. The Z Warriors all reflect on Goku's life. Mr. Satan emerges the savior of Earth, and Gohan goes off to tell his mother the terrible news about his Dad.