She thinks about how best to answer that.

"One time," she says, "we were called to a robbery where a security guard was murdered. It was during a blizzard, probably the worst New York had seen in decades. Sherlock didn't want to take the case. Thought it was too easy and they didn't really need our help." She leans forward a little. "Then the power went out. And suddenly it was enough of a challenge to keep him interested."