During a class field trip to an island in the middle of a lake, XANA conjures an aquatic monster to trap the students. However, Yumi, who stayed behind to do her schoolwork, is able to enter Lyoko where she must face William one-on-one.
Stars: David Gasman, Matthew Géczy, Mirabelle Kirkland
Director(s): Jérôme Mouscadet
Writer(s): Sophie Decroisette, François Deon, Thomas Romain