House of Anubis S02E55 - House of Oblivion

Fabian is now unable to remember his own name - he even forgets who Nina is. Vera plants the ox bell in his room, but hears Nina and Fabian coming so she hides in the closet. They find the ox bell and take it to the tunnels, completing the task, curing them all. But their celebrations are short lived as Victor and Vera hatch their plan, leaving Nina and her friends to walk into a trap. Victor and Vera's plan backfires, leaving the Sibunas to return the Ox Bell to the Library.