Well, long story short, Nick disappears without a trace. Literally, it's like he just disappeared. Judy and the ZPD look for him for months, to no avail. Then one night, Nick visits Judy in a dream, and explains to her that he was somehow pulled into a shadow dimension, and that he will not be able to resist it's influence for much longer. He warns her that the next time they meet, he will no longer be himself, and that she would need to run from him.

When Judy wakes, she decides that it was just stress, and decides to take a vacation back to Bunnyburrow for a while, in the company of her family. Eventually, during the night, Judy wakes up to someone screaming "RUN". She turns on a flashlight and sees Nick, or what used to be him. His body is like a pure black shadow, and his eyes pure white. He advances on her, and she makes the fatal mistake of not running, and... Well, it's implied that he either killed her, or turned her into whatever he is.