chunk: Once into the book, the 17th century framing is mostly inconsequential. Instead, the story focuses on the future. The Sun has gone out and the Earth is lit only by the glow of residual vulcanism. The last few millions of the human race are gathered together in a gigantic metal pyramid, nearly eight miles high â the Last Redoubt, under siege from unknown forces and Powers outside in the dark. These are held back by a shield known as the "air clog", powered from a subterranean energy source called the "Earth Current". For millennia, vast living shapesâthe Watchersâhave waited in the darkness near the pyramid. It is thought they are waiting for the inevitable time when the Circle's power finally weakens and dies. Other living things have been seen in the darkness beyond, some of unknown origins, and others that may once have been human.