How I Met My Countess - Elizabeth Boyle

Lucy Ellyson, the improper daughter of an infamous spy, saves the life of the Earl of Clifton. He intends to make her his countess after the war ends, but when he finally is able to return to her, he finds that she's vanished.

Meanwhile, Lucy is living a new life in the heart of Mayfair. But she's as scandalous as ever, and when Clifton finally happens upon her, she's landed in the sort of trouble that only a hasty marriage can solve. He's more than willing to step in, but their future is all too quickly threatened by secrets from the past.