Code Lyoko follows four students at the fictional Kadic Academy: Jeremy Belpois, Odd Della Robbia, Ulrich Stern and Yumi Ishiyama. They discover a virtual world named Lyoko and a girl named Aelita living on it. There is also a computer virus called X.A.N.A. that does attacks on both Earth and Lyoko and puts everyone in danger. At the end of the first season Aelita is brought to Earth by the other four and becomes a student at Kadic. Everyone except Jeremy goes to Lyoko when X.A.N.A. launches an attack. Later seasons include students named William Dunbar and Laura Gauthier as Lyoko Warriors.