The Girl in the Blue Tunic (Hippo First Editions)

When Hannah's dad moves away to Saudi Arabia for his work, he moves Hannah to a posh privat school where her mother once went. Just when Hannah starts settling in a little girl starts to appear about the school, but nobody seem to notice her. Warning her to get out the school, she keeps egnoring her and keeps coming back. Hannah not knowing what to do tells her roommates....but was that the right decision?