“Some family members think I’m insane for coming back here,” Cassens said, walking through the sunny streets of Menton, France, in full black attire. It was her latest visit on a yearslong quest to prove that the city had mishandled her grandfather’s legacy — a quest that also pushed her to embrace a more aggressive side of her personality.“Nut up,” she said she’d been telling herself. “You are going to have to get over this anxious feeling of being perceived.”