They followed the sound, their footsteps cautious, leading them to a large bookshelf. The noise grew louder, a soft mechanical whirr that seemed out of place in a vet’s office. Ruby’s eyes widened as she noticed an anomaly.
“Susan, look,” she whispered, pointing to a gap at the edge of the bookshelf. The gap suggested the bookshelf wasn’t fixed to the wall as it should be. Susan’s breath hitched. “A secret door…” she murmured, her heart pounding. With trembling hands, she tugged at the bookshelf.