Oh no — his sister. In order to respond to a comment like that, she really needed to know who his sister was. Which meant that she needed to know who he was, which she didn't. It was going to be obvious now, no matter what she said. If she asked who his sister was it would turn out that she was someone Henri knew well and had probably gone to school with, because that was just her luck with these sorts of things. If she tried to make some pleasant but vague remark about his sister, she might get caught saying something that didn't make any sense in context and give herself away that way. No, there was no way forward, and this conversation had ceased to be easier than striking out on her own. It was time to leave.

"I'm so pleased to hear it," she said, with a too-wide smile. "Well, thank you for the well-wishes. I'll be off to —" find my brother is how she intended to finish that sentence, but she had decided to start walking before she'd finished it and someone had apparently stepped on the train of her dress again without her noticing, which meant when she tried to take a step she found herself instead pitching forward towards this stranger, in probably the least graceful way anyone could ever have managed.