Ostia is gripped by fever in the seventh title in this bestselling series, and the four young detectives receive a summons from the Emperor. Does he have a new adventure for them?

Jonathan's father, Doctor Mordecai, is summoned to Rome to help the plague victims. The four young detectives are wanted too, as the Emperor Titus believes that they can find the mysterious enemy who seeks Rome's destruction.

Can the friends prevent disaster? And what is Jonathan's secret mission?

"Immensely readable" - TIMES EDUCATIONAL SUPPLEMENT

"The story is so well paced and involving that you don't realise just how much information you are absorbing" - SCHOOL LIBRARIAN