Your heroine is chasing someone. She’s running hard, dodging obstacles and gaining on them. They run down an alley. It’s a dead end. She’s reaching for her gun and slowing down. She notices that the person she’s chasing isn’t slowing down. In fact, if they keep going they’re going to run right into a brick wall. They keep going. She stumbles as the person disappears through the wall. Stunned, she runs to the wall and touches it. It’s….

Who is she chasing and why? For example, is she a cop, a bounty hunter, a private detective? Did they steal something from her?

Where is she? What city?

What happens when she touches the brick wall? Is it hard brick? Does her hand go through the wall? What’s on the other side of that wall?