After discovering their ability to time travel and narrowly escaping the Siege of Kerak, best friends Ashton Sinclair and Imogen Blaine decide to embark on a new adventure in the past. They appear in ninth century France, amidst the tumultuous twilight of the Carolingian Empire. Without a real plan as to what to do on their historical vacation, a chance meeting with a young Frankish princess on a bloody mission sends them spiralling into a plot of rebellions, espionage, and mystery. The empire, and the future of Europe itself, hangs in the balance. The stakes are higher than they know. But does the road they walk carry too high a toll?