When a mysterious signal pulses through the Earth, scientists at secret facilities around the world realize something impossible has begun. The signal isn't coming from space. It is coming from beneath humanity's feet.
In Atlanta, former scientist Dr. Elias Kane recognizes the pattern immediately. Eleven years earlier, Kane was involved in a classified experiment that ended in disaster and left dozens of scientists dead. He walked away from science, changed his life, and tried to forget what happened.
But the past has found him.
As communications collapse and strange black structures begin emerging from beneath cities, oceans, deserts, and mountains, Kane receives a warning from Lena Cross, a woman who was officially declared dead years earlier.