The sound of the flat's front door opening, followed by heels on hardwood, is audible in the kitchen.

(It isn't quite true that Jim is the only one who can break into this flat. He's just the only one who ever does. Usually.)

Irene Adler is drawing a breath to say hello as she enters the room, but she pauses instantly as she picks up on the atmosphere. Something is going on.

She cocks her head and stays silent, waiting to see what it is.