Rosemary and Laura are called to Rowfield to find out the cause of a mysterious blight, which only seems to affect the plants from gardens competing in the local open day competition. The competition is fierce between those after the first prize and the duo soon discover that the competitors are blaming each other for the troublesome blight. Suspecting the soil in each garden is being contaminated by weed killer as an act of sabotage, Rosemary and Laura discover the competitors will do anything to win, when they come across the dead body of last years winner Mr Westwood...