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...

M. G. Leonard is an award-winning, bestselling writer of children's books, as well as a member of Authors4Oceans. Her books are sold in 40 countries, and there is currently a TV series in development based on her Beetle Boy series. Her first picture book, The Tale of a Toothbrush, is out now. She is also co-author of the critically acclaimed Adventures on Trains series. Before becoming a writer, M. G. Leonard worked as a digital media producer for the National Theatre, The Royal Opera House and Shakespeare's Globe.