It had been months since the night Victoria Walker disappeared into the black liquid, and Elias Thorne’s ghost became something far more dangerous. The thing now called the Collective Echo was locked deep inside the secure facility. They’d built a special chamber for it; a cage within a cage, wrapped in exotic metals and lined with electromagnetic pulses designed to keep it quiet. Still, even in its silence, the Echo didn’t feel dormant. It gave off a strange, low hum like it was breathing.

Maya and Ben had buried themselves in the study of it. What had started as fear quickly turned into obsession. Day and night, they worked in...