The first day at a new school is always strange. But for Martha Crumble, this is no ordinary school. And as she will come to learn, she is no ordinary person. After an encounter with a strange cat, a message from a peculiar library book, and a trip down the roots of an ancient tree, Martha finds herself in the mysterious world of Dendro; a world inhabited by gnomes, trees, talking animals, and magic. Dendro is under aCack and Martha and her friends must find and close a mysterious doorway in order to save, not only the world of Dendro, but also their own. Fears must be overcome, courage found, and sacrifices made, in this magical and thrilling adventure where worlds are entwinned, and nothing is ever as it seems.