After discovering The Carthage Region, the group decides to explore it. Yumi is forced to opt out after her continued late-night trips to Lyoko draw the attention of her parents. While on The Carthage Region, Ulrich and Odd get dematerialized but don't appear in the real world, so Yumi sneaks out of the house to go to Lyoko and rescue Aelita from the Scyphozoa while Jeremie searches for a way to recover Odd and Ulrich. Unfortunately, Yumi's parents discover that she is missing and alert the school, who in turn discover that the other four are missing as well.