The Angel of Avondale Abbey by Nadine Millard

James Harrington has always done what was right, what was good, earning himself the title of Angel of Avondale. His life has followed the exact course it should, with nothing ever getting in his way. That is, until a mysterious letter from Vienna arrives and turns his world upside down.
Senna Baker never thought she’d find herself running for her life, heading for a place she’d never even heard of, let alone seen. But she’s run out of options and now the only person who can help her is the Marquess of Avondale.
James and Senna find themselves in circumstance they never could have imagined. And with a niece to protect, it’s vital that they get to the bottom of the mystery they’ve become embroiled in. Fighting an unknown enemy is hard enough. But for the Angel of Avondale, fighting the devilish attraction to his unexpected guest is proving almost impossible.