The Summoning by Lynne Ewing

Meri, Sudi, and Dalila are three girls who live in Washington, D.C., but have little else in common. Or so they think. When an ancient magic is revealed, so are their true identities as Sisters of Isis.

The Summoning

After receiving an anonymous invitation to dinner at the Sky Terrace, Sudi meets a mysterious guy named Abdel, and two other girls, both strangers. Sudi doesn't know whether to laugh or run when Abdel claims that she and the other girls are the descendants of Egyptian pharaohs, powerful ancestors who have given them magical gifts and powers of transformation. But when evil forces begin to threaten her world, Sudi has no choice but to believe.

Divine One

It's bad enough that Meri had to leave her laid-back life in California for a snobby prep school in Washington, D.C. Now her mom, Senator Stark, has decided to run for her party's presidential nomination, and Meri is being forced into the spotlight more than ever. But while Meri dodges the paparazzi, the Sisters' newest enemy-Apep, the Egyptian god of darkness and chaos-is on the loose, devouring innocent people and bringing unnatural storms. Meri knows he must be stopped. But have things already spun too far out of her control?