"Charlie is smart," she says. "It will be fine."

With Renee, maybe, that conversation would be a struggle, but Renee isn't sensible the way Charlie is. It's one of the reasons their marriage didn't last.

"So of course I have no intention of breaking curfew on purpose, but in case of circumstances outside my control, what else do I need to know to defend myself?"

(Her gaze flicks, briefly and without her permission, to Sherlock's scar.)