On a school trip to the Royal Swan Natural History Museum Ava finds herself at the centre of a
heist: hundreds of invaluable bird of paradise skins from the Alfred Wallace Collection have
been stolen! When she discovers a large jet-black feather she's sure it's a clue but the
police won't listen to her. Slipping away she takes the case to the Twitchers in a
investigation that leads them to the bizarre and sinister world of fly-fishing and to a
mysterious girl with a pet Raven called Caliban and a dangerous ring of thieves and
smugglers...
