Saint's Gate by CARLA NEGGERS

Emma Sharpe is summoned to a Maine convent, partly for her FBI art crimes work, partly because of her past with the Order. At the centre of the issue is a mysterious painting of Irish lore and Viking legends. But when the nun who contacted her is murdered, it seems legend is becoming deadly reality.

Colin Donovan is one of the FBI's most valuable deep–cover agents. Back home in Maine after his latest mission, a contact clues him in to an intrigue of murder, international art heists and long–held secrets that is too tempting to resist. As danger spirals ever closer, Colin is certain of only one thing– Emma Sharpe is at the center of it all.