A cave-in traps Nils, another crewman, and a little boy in a tunnel. While Dave and others work to dig them out, Calhoun and Barnabas rush to retrieve a batch of nitro to free them. But their trip becomes more dangerous than ever when their wagon wheel collapses and they must seek the help of a preacher who believes they are damned, and someone else who is determined that they not make it back alive.