Danny Fantom Sezon 2 Odcinek 8: The Fright Before Christmas

Vlad is back, only now he's dying of ecto acne, a direct result of the lab accident with Jack and Maddie years ago. To ensure Danny helps him find a cure, Vlad infects Sam and Tucker, forcing Danny to turn to Clockwork to help. He heads back in time, to the college days of his parents and Vlad, to make sure the accident that injures Vlad never happens. Only by doing so, he changes the present - now Maddie's married to Vlad and living in Wisconsin, and Jack's an evil ghost named Jack Plasmius!