Third in the series (The Long War, 2013, etc.) exploring the idea that alternate Earths exist and can be visited simply by “stepping” into them.
The discovery of the Long Earth by folks with a natural ability to step, and its subsequent opening up to everybody by means of a simple device, resulted in a diaspora. The original Earth, known as Datum, still has its troubles, and this time, the supervolcano beneath Yellowstone explodes to catastrophic effect, hastening the dispersal of Datum’s population. The building of airships equipped with rapid-step devices means various Earths thousands or millions of steps from Datum can be reached. U.S. Navy Cmdr. Maggie Kauffman receives a commission to explore beyond Earth 200 million and in the process discover what happened to a previous expedition that never returned. The inventor of the stepper device, Willis Linsay, invites his daughter Sally, a loner and a natural stepper, to join him on an expedition to explore the Long Mars—where, he deduces, somewhere among the alternate Marses there will be intelligent life. And Lobsang, the supersmart AI who generally keeps an eye on things, suspects the emergence of a superior species of human. These highly intelligent individuals call themselves the Next, refer to regular humans as dim bulbs, tend to antagonize everybody and seem to originate in a particular location on one of the distant Earths. Foreseeing an inevitable conflict, Lobsang asks natural stepper Joshua Valienté to investigate. For series fans, the technique is familiar enough: a sprawling, meandering narrative whose purpose is less to amaze and entertain than to inquire about humanity itself and how attitudes and approaches to existential questions might or might not change.
Panoramic and fascinating, if sometimes vexingly discursive.