Mikayla and her brother, Calvin, are about to get into deep trouble. After accidentally stumbling into an abandoned mine, they are surprised to find that they are not alone. They are even more shocked to discover that whatever is lurking in the mine shafts deep beneath the city of Calumet, Michigan, isn't human. While trying to find a way out of the mines, Mikayla and Calvin become lost, but they're certainly not alone. Giant, hideous copper creatures are lurking in the depths, searching for their next victims. It's a race through a dark, dizzying maze as the pair desperately try to find their way out of the mines and back to the surface ... before the copper creatures find them first!