|Air date||March 25, 2013|
|Written by||Josep Maria Roca Peña|
A Travel Through Time,
The episode begins in the room of Ulrich and Odd, and Jim wakes them. In Yumi's house, her parents tell her they'll be out all day for work, and that she should take care of his younger brother, Hiroki. Yumi is accompanying Hiroki at school, and he starts talking about her relationship with Ulrich. Once in the cafeteria, Jeremy informs Lyoko-Warriors the new Skid will be more powerful and can become invisible, and after school they will prove it. Yumi cannot go with them because she must take care of her brother and her house.
In physical education class, are Aelita, Odd, Ulrich, Jeremy and Sissi's clone, and Sissi Jim says Sissi is doing the class better than Jeremy. When the class ends, they go to the factory and it rains a little. Ulrich has a hunch that X.A.N.A. will attack during the mission, but in the laboratory Jeremy don't detect any activated tower. Aelita, Ulrich and Odd are virtualized in Sector 5 and go to Skid room, where they see the new Skid. All three are mounted on the Skid and depart for the forest sector. Jeremy activates a program and Skid enters into the Digital Sea.
In Yumi's house, Hiroki tells his sister to play a game, but Yumi is denied. Then Hiroki says that if they don't play, he will tell their parents that Yumi is irresponsible and don't can take good care of the house and her brother. The rest of the group, once on the Digital Sea, Jeremy gives the coordinates of the new Replika. When preparing to enter, X.A.N.A. activates a tower in the ice sector and they have to return to Lyoko. Jeremy says they will return to the Replika other day, and now the priority is X.A.N.A.
The Skid enters the ice sector, and Jeremy calls Yumi warning her of X.A.N.A. attack. Hiroki doesn't allow Yumi to leave, and Jeremy uses voice synthesis to simulate his father saying Yumi allow it to go, and when Hiroki gets to ask questions, Jeremy says there is a tunnel and ends the call. Aelita puts the Skid near the tower and landed, and then it becomes invisible. Yumi arrives at the Factory, and Jeremy virtualizes her. Then there are Bloks, flying Tarantulas and Mantas. Odd goes fight against the Bloks saying "I will unblock this". Ulrich goes fight against the Mantas, Yumi goes fight against the Tarantulas and Aelita tries to go to the tower. But X.A.N.A.-Sissi appears.
Odd destroys all the Bloks and goes for Mantas, climbing on a Manta. Ulrich is fighting against X.A.N.A.-Sissi and he is devirtualized but Yumi devirtualizes X.A.N.A.-Sissi. A Tarantula devirtualizes Yumi, but Odd makes his Manta dsvirtualize another Tarantula. At the end Odd destroy all Manta and almost all Tarantulas, but the last Tarantula devirtualizes Odd. Aelita devirtualizes the remaining Tarantula with an energy field and goes to the tower, for deactivate it.
In Yumi's house, Hiroki's parents ask how he's alone at home, and when he says they called him, begins suspect. Yumi then appears, and manages the situation. Hiroki said Yumi is very responsible, because he promised this if she plays with him.