War has come to the Long Earth. . . .
Humankind has spread across the new worlds opened by explorers Joshua and Lobsang a mere decade ago. Now "civilization" flourishes, and airships link the multiple Earths. A new America christening itself "Valhalla" has emerged more than a million steps from the original Datum Earth. Like the American revolutionaries of old, the Valhallans resent being controlled from afar. And in the wake of humankind's advance, the trolls--graceful, hive-mind humanoids whose song has suffused the Long Earth--are beginning to fall silent . . . and disappear.
Joshua, now married and a father, is summoned by Lobsang. It seems he alone can confront the perfect storm of crises that could plunge all of the Long Earth into war--a war unlike any that has come before.