A black barrier, traversable by humans, with monsters lurking within.
That was identical to the phenomenon they had encountered on their way here. He hadn't expected that very same thing to manifest near P City Base. If those monsters were to make an appearance, there was no telling whether the base would remain safe.
"What are you thinking about?" Fiona asked curiously, seeing Mark lost in silence.
Mark cast a glance at her and replied softly, "What you described... I saw it on my way to the base as well."
"What?" Shock registered across Fiona's face as her expression turned grave. "There's black mist in other places too?"
Mark nodded. "That's right, and in more than one location."
The casual air faded completely from Fiona's face, her tone turning increasingly solemn. "How many did you see?"
"On my way here, I saw two," Mark said, adding, "There were monsters inside those as well."
Fiona drew in a sharp breath.
