An ice queen has returned to Earth to create a world of ice and stillness, but the real plot is that Luna has found somebody she loves. Yet, she is a cat, and he is a human. Doesn't exactly work all that well.
However, the movie worked out pretty darn good. I liked the focus on the romance, instead of the focus being on yet another alien trying to take over Earth. It was a nice shift, and the two plots were weaved together quite well.
I felt as if I learned so much more about Luna as a character, and there were a few moments I wanted to cry with her. Very touching.