I should probably go read another Dan Brown novel featuring Professor Robert Langdon. Kennedy's James Acton seems very similar, almost derivative. They both write about professors of antiquity who get drawn into religious mysteries. In this one, James Acton and his wife Laura Palmer, another professor of antiquity, are invited to a chateau in France to retrieve The True Cross. Of course, Acton is injured and his wife is the rich, SAS-trained killer who saves them both. I do enjoy a strong female character, though, so I don't mind that repeating theme.
Kennedy's Acton/Palmer books are fast paced, action-packed, and well-written. If you like thrillers based on finding religious artifacts, you should like this lot.