Aquarius descending - Martha Lawrence

It's a common California tragedy: a young woman has disappeared into the Bliss Project, a religious cult, and psychic detective Elizabeth Chase is asked to find her when other investigators have failed. There's only one catch: the missing woman is her lover's former fiance, and Elizabeth isn't sure she wants to save her.

Relucantly, Elizabeth infiltrates the cult and discovers a heady mix of sex, drugs, rock'n'roll - and evil. By the time she knows how evil, she's in deep trouble: the cult's rulers have psychic and seductive powers equal to her own