His Holiness needs to meet Museum Detectives, Mr and Mrs Wilson, urgently.
It's been two years since Daniel and Abigail Wilson visited the Eternal City, and this time they're invited by none other than Pope Leo XIII himself. But this is no sightseeing visit, as the renowned detectives are asked to put their skills to good use, investigating a suspected assassination attempt from within the Vatican's walls.
Who can be trusted when murder could come from any direction? As the detectives begin to delve into the workings of the Vatican they encounter all manner of threats, with possible Mafia involvement likely. It seems not everyone views the presence of two British non-Catholics as welcome in such matters, and they certainly do not appreciate them meddling in finely laid plans.