Leonora shouldn't be building a submarine in a tree. Or illuminating the local wildlife. She should be keeping her head down, going unnoticed. Because Leonora Bolt is a SECRET inventor. However, she can't stop thinking about the clues she has found that might lead her to her parents. So, while hiding in Snorbury and desperately trying to avoid her wicked uncle, Leonora devises a plan. She might need to steer a submarine she built herself, with only a few friends and an otter with particularly sensitive whiskers as company – but once disaster knocks on their door, Leonora's crazy plan proves to be the smartest she has ever devised…