Eliza Willard. The Power of Three (1999) 181 pp. [pbo]
Publishers description: Prue, Piper, and Phoebe Halliwell [of San Francisco] didnt think reading a magical incantation would really work. But it did. Now Prue can move things with her mind, Piper can freeze time, and Phoebe ca see the future. They are the Charmed Ones—the most powerful of witches. But being enchanted has a price. Theres a warlock who wants to steal their powers. And hell do it any way he can—even if it means killing them! Based on the WB Network television series, Charmed, created by Constance M. Burge.
Setting: San Francisco