William Whooper intends to destroy natural life of Secret Valley. When the rogue is hatching a plan to carry out his plan appears godsend Paula, a most unusual young naturalist and vegetarian who is camping in the valley.

In the course of a battle between the boys of Secret Valley and the gang of "Spider", old Dan joyfully announces that Rosa has won a major writing prize. Rosa will have to go to Sydney to collect her award from the Spanish consul.