Scarlet and Ivy, The Dance in the Dark - Sophie Cleverly

For twin sisters Scarlet and Ivy, boarding school has been a horrid mix of murderous headmasters, painful punishments, and vicious classmates. But it's a new year, and things are looking up. The kindly Mrs. Knight is in charge, their classmates have been civil, and the weather is even brightening up.

Then, when their beloved ballet teacher, Miss Finch, suddenly disappears and strange Madame Zelda takes her place, freakish things start happening. Poison letters are circulating around the school, and "accidents" are plaguing the students. It seems that the girls are in danger once more...

Is someone out for the ultimate revenge?