A Torn Allegiance by Jen Geigle Johnson

Peace is tenuous in the small kingdom of Oldenburg, and the looming threat of invasion from Napoleon weighs heavily on the royal family. Their country’s best chance for safety lies in strengthening their alliance with the English. So it is that Prince Hayes Wilhelm finds himself returning to England, where he hopes a prominent duke can help him protect his country.

Lady Elsie longs to make a difference in the world, but spying was not quite what she had in mind. So when her father, the Duke of Shelby, approaches her about keeping a close eye on the visiting crown prince of Oldenburg, she reluctantly agrees. But the outspoken young woman did not anticipate finding in Hayes a man who shares—and respects—her progressive ideas. Their mutual attraction is undeniable, but Elsie cannot forget her charge to spy on the man who is quickly stealing her heart. With the threat of war looming ever closer, Elsie and Hayes must consider carefully whom to trust—before their secrets tear them apart.