Checkmate (The Septimus Series)

Rhitha's life is miserable - but then she meets Bina. Rhitha's sister has been bullying her all her life, for no reason that Rhitha can see. But when they move to Ruph, there is a new friend in Rhitha's life: with the help of Bina and her unique powers Rhitha begins to see that there might be more going on in her family than meets the eye. There is a secret nobody suspected... Things come to a head between Rhitha and her sister in a clash that draws in everyone around them. Are the peculiar forces at play in Ruph responsible for fanning their conflict? Who is the mysterious stranger that appears at Grandmother's door in the middle of the storm? And can Bina help Rhitha find the strength to stand up to the bullies and become who she is meant to be?