Celebrity recording artist and Moon Cockroach from the 2004 young adult science fiction novel The Princess of Neptune by Quentin Dodd.
She's to perform a concert at the Neptune Coliseum on uh, Neptune. Hunh. I guess Neptune just has the one coliseum, then.
Anyway she goes missing, and there's evil mind-controlling shenanigans, and at the end the protagonist and her friends get to be her back-up band.