Must Love Scoundrels (The Royal Saboteurs #4)
Shana Galen

For eighteen months, Duncan Slorach trained to be a Royal Saboteur. He's one of the best, and when he's finally offered a mission, he jumps at the chance. The only problem? His partner. For eighteen months, Duncan has been in love with Lucy Galloway. Unrequited love. The woman barely seems to know he's alive. Duncan is ready to put his feelings aside and concentrate on the assignment, but that proves impossible when Lucy and Duncan are forced to spend long hours alone together and begin to build a friendship. Surely, if he could just kiss her, she'd realize she has feelings for him too.
As Lucy and Duncan draw closer to discovering the traitor in their midst, they realize nothing is as it seems – with this mission or their relationship. In fact, Duncan isn't the villain Lucy has made him out to be. In fact, he might just be the scoundrel she's been looking for all along.