There's one more obvious change: Shaw is no longer looking at him like he's someone she'd just as soon pass off to someone else. Harold had said to think of Bossie as a number, which would involve more attention in and of itself - but most numbers are strangers, unconnected to any of them. This guy is a number in the way Grace had been; the way Arthur Claypool had been. He's significant to someone who is significant to her.

But there's no time for introductions, because she's already heading down the hall, half her attention on him and half on the source of that bang. "Maybe. I didn't see anything."

She runs her fingers down the doorframe once she's reached it, then walks backwards, anticipating that the ghostly banging will move along to the next door. Instead, it sounds all the way at the far end of the hall.