Creating a Bezier Path at Z axis

Hi,

I am new to Motion and have been facing some issues. I have a birds-eye view image of a project with some buildings. I plan to run a streak of light on the building outline to highlight individual buildings with background VO with the camera zooming in slowly. When I use the bezier tool to draw the outlines, all seems good unless the camera zoom in. The issue is with the camera zoom the, outline loses its place. When I checked the same from the top view, I saw that the image plane and the bezier point are not on the same plane and I am unable to start the beizer tool as same as the image plane.

How do I start to draw the bezier on the same point of the image on the Z axis? Am I missing something?

thanks