The Summoning (Sisters of Isis, #1)

Following the incredible success of "Daughters of the Moon," Lynne Ewing has created an all new fun and hip teen fantasy series.
Based in Egyptian mythology and set in modern-day Washington, D.C., Sisters of Isis follows the lives of Meri, Sudi, and Dalila, three fifteen-year-old girls who have just discovered they are descendants of very powerful ancestors-Egyptian pharaohs. From these ancestors they've inherited magical powers of transformation, the ability to cast spells from the Book of Thoth, and, as they will soon learn, the responsibility of protecting the world from the evil forces of Chaos.