Hawkthorn's underground tunnels are heaving with secrets but that's not all they're hiding. Twelve-year-old eco-activist turned detective Ava Frylander doesn't remember falling over the cliffs into the raging waterfall at Laureleaf Park. All she knows is, Tony is dead and it wasn't an accident. She braves Hawkthorn's grungy underground tunnels, where, according to local legend, souls of the recently departed roam - hoping to conjure her best friend's ghost and identify his killer. There she spies spectral thugs dressed in old-timey clothes before being chased out by a groaning black shadow. When she's chased off by a groaning black shadow, Ava manages to escape, but she's not the only one who emerges from the tunnels.