Margery Allingham 
Sweet Danger 

Nestled along the Adriatic coastline, the kingdom of Averna has suddenly, and suspiciously, become the hottest property in Europe, and Albert Campion is given the task of recovering the longmissing proofs of ownership. His mission takes him from the French Riviera to the sleepy village of Pontisbright, where he meets the flamehaired Amanda Fitton. Her family claims to be the rightful heirs to the principality, and they insist on joining Campion’s quest. Unfortunately for them, a criminal financier and his heavies are also on the trail. The clock is ticking for Campion and his cohorts to outwit the thugs and solve the mystery of Averna.