The Haunting — Lynne Ewing

Meri, Sudi, and Dalila are three girls living 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.

Strange  things are happening to Sudi. And when her date with her new crush Raul turns into a huge disaster, Sudi can't deny the truth anymore -- she's got a ghost on her hands. But instead of being scared, Sudi sees this as an opportunity; it's like having a special pet that can spy for her and play tricks on her nemesis, Michelle. Only this friendly ghost turns out to be not so friendly, and Sudi quickly discovers that it is actually a mut, one of the dangerous dead who tormented the ancient Egyptians.  Sudi, Meri, and Dalila are soon caught up in the spirit's brutal plan to wreak havoc in the world.  Will the magic of the Sisters of Isis be strong enough to stop it?