Deeper

In TUNNELS, boy archaeologist Will Burrows went in search of his missing father--and discovered a sinister subterranean world. Now, wandering the dark, hot bowels beneath the Colony with his best friend Chester and his brother Cal, Will stumbles across the Styx's dastardly plan to exterminate all Topsoilers by unleashing a lethal plague. Slowly he begins to piece together the plot. But how can Will save the Topsoilers from annihilation when his own life is at risk--and his killer stepsister is still at large?