After failing with an army of rats, X. A. N. A. attempts a similar tactic using hornets. Meanwhile, Ulrich gets a letter from Yumi saying that she loves him. He's not quite sure how to respond, so he avoids talking to her about it. Jeremie and Odd find out about the note, but don't learn who wrote it. Ulrich tells them not to tell Yumi. After learning about the hornets and X. A. N. A.'s control over them, the group heads for the factory. Ulrich talks to Yumi about the note and tells her that he feels the same way, only to find out that it was Sissi who wrote it. In Lyoko, Ulrich's reaction to the discovery leaves his performance lacking as the hornets move on the school.