Aelita adjusts to life in the real world, while Jeremie attempts to develop an anti-virus program for her in an attempt to fully liberate her from X. A. N. A. 's power. On Lyoko, a fifth sector is discovered and the group explores more of Lyoko's secrets and mysteries. The gang begins to uncover information about a mysterious man named Franz Hopper, who went missing ten years ago, supposedly created the Supercomputer, Lyoko, and X. A. N. A. , and claimed to be Aelita's father. The quintet eventually discovers that Franz Hopper is indeed alive somewhere, hiding deep within the uncharted parts of Lyoko to avoid X. A. N. A. further. All the while, X. A. N. A. attempts to steal Aelita's memory using a special monster, the Scyphozoa, in order to gain the Keys to Lyoko and free itself. At the end of the season, Aelita and Jeremie discover that Aelita does not have a virus, and instead is missing a fragment of herself, consisting of her lost memories. In "The Key," X. A. N. A. tricks them with a fake fragment and succeeds in stealing Aelita's memory and escaping the Supercomputer into the World Wide Web, which exists in the Digital Sea outside of Lyoko. Aelita appears to perish as a result, but is revived when Franz Hopper gives her his faction of the Keys to Lyoko and restores the hidden memories of her forgotten childhood before being virtualized on Lyoko.