After the cataclysmic upheavals of Step Day and the Yellowstone eruption humanity is spreading further into the Long Earth, and society, on a battered Datum Earth and beyond, continues to evolve. Lobsang now understands the enormity of what's taking place beneath the surface of his earth - a threat ...

After the cataclysmic upheavals of Step Day and the Yellowstone eruption humanity is spreading further into the Long Earth, and society, on a battered Datum Earth and beyond, continues to evolve. Lobsang now understands the enormity of what's taking place beneath the surface of his earth - a threat to all the worlds of the Long Earth.