A Love in Disguise by Cara Hart
The letter from her brother warned her of danger, but Kate Carteret is doubtful until she discovers her bedchamber in ruins. In the face of an unknown threat, she flees her home and finds sanctuary as companion to a family friend. But Kate's peace is soon shattered by the arrival of the Earl of Ashton, a man with a few secrets of his own.
Though retired, James Meredith has unwillingly accepted one last mission for the Crown - locate a dead colleague's sister, who may hold the key to the identity of a traitor. Her trail leads to the home of his cousin, in a tiny village in the north of England. His aunt's new companion, a middle-aged spinster, should be easily dismissed. Why can he not get her out of his head?