Code Lyoko - Season 1 Episode 14 -

It's been a year since the group first discovered the supercomputer and Aelita, and they decide to throw a surprise party for Aelita. Sissi catches wind of the party and follows Ulrich and Yumi to the factory. On the way there, X.A.N.A. possesses the factory as a whole. X.A.N.A. traps Ulrich, Yumi and Sissi in the elevator and drops them to the bottom of the shaft.