"Begins with a bang and the pace never falters."*

At long last reunited with his dad, Will now spends his days exploring the land of the "second sun," decoding the cryptic glyphs on its three mysterious temples -- or eyeing the wild animals with renegade girl Elliott.

But an army of darkness is on the march. And the ruthless Rebeccas have once more cheated death. With a corps of cold-blooded Limiters at their command, they're determined to hunt Will to the bitter innards of the earth.

Closer to victory, or closer to death? This time, who won't escape with their life?

The fourth book in the New York Times Bestselling TUNNELS series.