Description Join best friends Katy, Cassie, and Zia on a series of amazing adventures as they work together to save the planet... The friends' latest adventure takes them to an enchanted forest where they set out in search of the biggest horse chestnut in the world. But all is not as it seems. The trees around them are dying-and where are the animals? As they try to work out a way to help, the girls discover how vital trees are to all life on Earth.