Jimmy is eleven years old, full of bounce and enthusiasm, an inventor and something of an entrepreneur. He lives in suburban Sydney with his widowed mother, Maria, who earns a meager living doing sewing at home for a local garment maker. Jimmy contributes to the family income by collecting kitchen scraps and garden refuse which he converts into compost and then markets through a local plant nursery.
But his activities have brought him into conflict with Bet Draper, a spiteful neighbor, who tries to close down his little business and, when she is unsuccessful, begins a campaign of harassment designed to force Jimmy and his mother to move elsewhere.
Meanwhile, Jimmy has met Sam, a one-time engineer in his early fifties who retired early due to his failing eyesight. Sam is taken by Jimmy’s confidence and eventually commissions him to design and build an automatic feeder for his pet chickens. in the process Sam meets and becomes smitten with Maria.
The harassment continues with anonymous phone calls to the Tax department, Maria’s employer and Social Security. While all this is going on, Jimmy discovers that the water near home is polluted with oil. Along with the help of some friends, they track down where the oil was dumped and manage to catch the polluter in the act. It turns out to be Bet Drapers husband. Jimmy and his friends win a special reward for their ecological detective work, the chicken feeder is sold to a local manufacturer and Sam and Maria finally go out on a date.