Pirate Girl by Cornelia Funke
Ferocious Captain Firebeard may think that he and the cruel crew of the Horrible Haddock rule the high seas - but he hasn't reckoned on a small, daring girl called Molly. And he certainly should never have kidnapped her! Molly soon proves to be sharper and quicker than any of the pirate gang's cutlasses. And before long, Firebeard must face his comeuppance - the fury of her fearsome mum!