Offer both from Amazon and Kobo, From Turtledove, another Alternative History novel. Do not know if standalone or part of a series.
https://www.amazon.com/Through-Darke...gateway&sr=8-1
https://www.kobo.com/us/en/ebook/through-darkest-europe
Spoiler:
From the modern master of alternate history and New York Times bestselling author Harry Turtledove, Through Darkest Europe envisions a world dominated by a prosperous and democratic Middle East—and under threat from the world's worst trouble spot.
Senior investigator Khalid al-Zarzisi is a modern man, a product of the unsurpassed educational systems of North Africa and the Middle East. Liberal, tolerant, and above all rich, the countries and cultures of North Africa and the Middle East have dominated the globe for centuries, from the Far East to the young nations of the Sunset Lands.
But one region has festered for decades: Europe, whose despots and monarchs can barely contain the simmering anger of their people. From Ireland to Scandinavia, Italy to Spain, European fundamentalists have carried out assassinations, hijackings, and bombings on their own soil and elsewhere. Extremist fundamentalist leaders have begun calling for a "crusade", an obscure term from the mists of European history.
Now Khalid has been sent to Rome, ground zero of backwater discontent. He and his partner Dawud have been tasked with figuring out how to protect the tinpot Grand Duke, the impoverished Pope, and the overall status quo, before European instability starts overflowing into the First World.
Then the bombs start to go off.