Olga spots a new addition to the garden, but what or who could it be? It looks like the Sawdusts have another tortoise! Olga sends Graham to find out more about Bessy, and when he returns, Olga can see Graham is in love. But when the true nature of Bessy is revealed, Olga doesn't know how to tell Graham that she's really a bike helmet. Olga's elaborate tale of space-travelling tortoises helps Graham come to terms with Bessy's mysterious disappearance.