In Deeper, Jeff Long takes us back into the underworld he created in The Descent. (Both of which are most likely based on Journey to the Center of the Earth by Jules Verne).It is ten years after a plague destroyed all of Hadal life in the tunnels that run under the Earth's crust. There are settlers and entrepreneurs all over the deep.
One film maker and his crew are following the route of the Helios expedition (from the first book) to create an IMAX film called "Hell." There are other teams also exploring the deep, including a NASA subterranean team that is mapping the largest fresh water lake on the planet.
But something is still killing off the settlers and explorers. At the same time, something is drawing people into the tunnels. Could it be that not all of the Hadals perished?
On Halloween, hundreds of children are kidnapped from the United States by monsters from underground. Now there is proof that Haddie is still alive. Teams are organized to find the children and bring them back.
But there are two snags to the planning - 1) the international peace treaty for the subterranean planet says no military may enter the tunnels; and 2) Ali Von Schade, one of only two people to survive the original Helios expedition, refuses to return to the depths.
Long, Jeff. (2007). Deeper. New York: Atria Books.
