Mrs.Elwood rapped sharply on the door.

The footsteps halted; after a few seconds the sound began again.
"She thinks we have come back," whispered Elfreda.
"So we have," smiled Grace, "with reinforcements." Her smile was reflected on the faces of her friends.

Mrs.Elwood, however, did not smile.

Two red spots burned high on her cheeks, her little blue eyes snapped.

Again she knocked, this time accompanying the action with: "Open this door, instantly.