Merlin has worked with the Kingsman probably longer than anyone else. Except for Arthur, of course, who recruited him when he was just out of Military School. But what happens when this cool, collected man finds himself in the company on the one girl who might see right through him? The enigmatic Ekaterina Duval is a mistery to everyone except for Harry, who for one never thought he'd see her again. As the ghosts from his past come back to haunt him, Kat-or Katie, depends on who's asking- will discover she might for once not be the smartest person in the room, and that perhaps not everything is as it seems when it comes to the quiet and serious Merlin.