C568 Beast Trap

"I caught the scent of gunpowder mixed with herbal medicine on the way here. It must have been left by the killer!" Zhang Xia pressed against the brick wall, inhaling deeply before patting it. "The scent vanishes right here. There could be a hidden door or a secret passage. Let's look for a trigger mechanism!"

As she spoke, Zhang Xia pushed against the wall to no avail