In order to re-organize the seed collection of famous botanist, Edwin Pargeter, Rosemary and Laura are called in by the current generation of Pargeters to help with the task. Their task is daunting, and it's not helped when a mysterious Chilean man is found dead in the back garden of the Pargeters' house. As they try to work out who the man was, they soon discover that something in Edwin's seeds is quite valuable, and that someone is out to get them, no matter the cost...