In book two, Jinx Valentine is reunited with her Humpty Dooish friends. The children are holidaying at the prized swimming spot, Coolabah Gully, and babysitting Mona the elephant at the same time. Their holiday is upset when Mona starts trespassing, stealing people's rubbish and bringing it home, and swimming till all hours. 

When Mona follows a roaming pony into the bush, the children run after her and get hopelessly lost. Navigating the bush without supplies or guidance puts them to the test. But, the real drama is lurking back at the Gully, or rather under it. What unfolds is irreversible, and will change the children forever.