S1·E14 The Trap

It's the anniversary of the day Jeremie and the others met Aelita. They begin planning a surprise for her, unaware that Sissi is spying. When Jeremie and Odd try to open the lab elevator, it won't work. They go to the control room to see what's wrong and XANA uses the machinery in the room to attack them. They escape and reach the lab basement. Meanwhile, Ulrich and Yumi get to the elevator. This time it opens. Sissi gets in with them at the last moment, but just then XANA causes the elevator to plummet down the chute. Yumi escapes to go join Jeremy and Odd in the lab. Back at the elevator, water leaks from the walls and begins to drown Ulrich and Sissi. Ulrich promises that if they get out alive, he'll be nicer to Sissi. Aelita manages to input Code Lyoko and reset time just Ulrich and Sissi begin to drown. At the end, Jeremie and the others present Aelita with an anniversary cake and Ulrich keeps his the promise he made to Sissi in the elevator.