May AD 80. Flavia and her three friends, Jonathan, Nubia and Lupus are in Cenchrea, the eastern harbour of Corinth, the hometown of Aristo, their tutor. But Aristo tells them he is not coming back with them this time. Later, there is a commotion, and the children find a blood-soaked Aristo crouched over Flavia's father, who has been stabbed. The children set off for Delphi in pursuit of Aristo . . .