The Jade Treasure of Shadows — Jason Ellis

The fourth book in the Amelia Maylock series. "I need to be careful." People in the old fashioned dimension were not familiar with magic of any kind. Amelia reminded herself that staying disguised was paramount. If she did find something wrong in the town square, Amelia knew she would need to decide quickly if she was going to react, or get out of there to safety. As she turned the final corner and saw the black iron fence ahead of her, it was clear straight away that something connected to her magical world was happening. A few feet in front of her, hanging in the middle of the road, all the way up to the fence, was an uneven line of white light. It had a distinctive blue tinge to it and looked as if someone had run along with a pen - that wrote in light - scribbling in the air. "I've never seen anything like that before!" Pretending to be totally unaware of it, and just a 'normal' girl walking home, Amelia followed the light trail towards the iron fence.