One half of the floor was uncovered without revealing the existence of any trap.

She attempted to pull the table into the centre of the room, better to roll the matting, but found it fixed to the wall, and going down on her knees, she discovered that it had been fixed after the matting had been laid.
Obviously there was no need for the fixture and, she tapped the floor with her little knuckle.

Her heart started racing.

The sound her knocking gave forth was a hollow one.

She sprang up, took her bag from the table, opened the little penknife and cut carefully through the thin rushes.