Code Lyoko (2003) : 1x24

One day at school, Jeremy notices that Odd, Ulrich, and Yumi are missing. Meanwhile, Odd, Ulrich, and Yumi ARE at school with Jeremy! What's going on? Turns out that XANA (in the form of Jeremy) has trapped Odd, Ulrich, and Yumi in a virtual world identical to the boarding school, completely at his mercy. With Aelita's help, Jeremy reaches the fake school and tries to convince his friends that he is the real Jeremy and that the imposter is XANA. When they learn that Jeremy got into the scanner to come here, XANA claims that Jeremy is the fake because he would never go into the scanner. But the others say that if his friends were in danger, he would. XANA gets angry and tries to crush everyone with wires and holographic zombies of Jim, Nicholas, and Herve. But Aelita destroys the false school just in time, foiling XANA's plan.