With safe seas, good roads, a common currency, and lots of interesting conquered territory, the Romans naturally invented tourism. They believed in a life of leisure - fine for those who could afford it - and some would set off on their travels for maybe five years at a time. As these ancient culture vultures descended on the sights, the tour guide was born to cater to their needs... 'Marcus, you must help me!' Stunned by a dramatic appeal from his otherwise cool mother-in-law, Falco cannot resist. His brother-in-law, Aulus, has been diverted from his route to Athens university by a man whose newly married daughter disappeared, with her husband, while visiting the Olympic Games as part of an extended wedding trip. Suspecting a classic cover-up, Aulus enrols Falco's help in solving the case. And of course his mother-in-law hopes to hurry her son along to university by passing the case over to Falco. Joining the rest of the married couple's tour group on the remains of their Grand Tour, Falco and Helena seize the opportunity to interview the owner/manager of 'Seven Sights Travel', as well as the other guests. Seemingly not getting very far, they can at least make the most of the splendid sights; but finally, on reaching Delphi, Falco and Helena unravel the mystery of the bride and groom.