The Awful Tale of Agatha Bilke by Sian Pattenden
Most girls are lovely. They put fancy ribbons in their hair, they collect kittens, they sing about helping hungry people (even the greedy ones). And then there's Agatha Bilke. Agatha is a pyromaniac - that's a girl who likes setting fire to things. She is mean and selfish and bent on causing harm. So her parents despair of her.