Spy for a Vicious Circle (The Adventures of Grant Scotland, Book Five) - The Adventures of Grant Scotland, #5

Rapid changes come to Aelfa, a city ruled by a foreign king but controlled by a crime boss. While King Reynard remains absent, the nefarious Mr. Quinn spreads his own influence and increases his power. Everyone in the city seems to be under his thumb, including the luckless Grant Scotland, caught in the middle of a web of intrigue and trying desperately to unravel the machinations of those thirsting to make a play for power in the once-proud ancient city.
When a mysterious foreign investor appears and buys up land under Quinn's nose, Grant is pulled into an ever-widening investigation of smuggling, corruption, and murder that will threaten to tear the city apart. As he prepares to make sure Quinn is out of the picture before the long hoped-for liberation of Aelfa by the forces of Zyren, he finds he must contend with not just one greedy villain, but an entire vicious circle of both friends and foes.