Overview
Deeper (sometimes known simply as Tunnels 2) is the sequel to the novel Tunnels, written by Roderick Gordon and Brian Williams.
The novel explores the events which Will, Chester and his friends have to go through to attempt to prevent the Styx from continuing their next phase of destruction upon the inhabitants of the Earth's surface.
Plot summary
Part 1: Breaking Cover
Will and Chester are overjoyed to be reunited once again as the Miners' Train travels down through the Earth on its way to the Deeps. Will's younger brother, Cal, is also with them. The train passes through a series of storm gates (gates designed to block powerful winds from inside the earth) and, on the final approach to the Miners' Station, the three boys jump from it. Having escaped detection at the station, they travel further into the Deeps, where they are attacked by carnivorous bats and are forced to take shelter in an old, deserted house. Inside the house they find evidence that Will's stepfather, Dr. Burrows, has already been there.
From Wikipedia (CC BY-SA 4.0).