The Long War (Long Earth 2)

A generation after the events of THE LONG EARTH, mankind has spread across the new worlds opened up by Stepping. Where Joshua and Lobsang once pioneered, now fleets of airships link the stepwise Americas with trade and culture. Mankind is shaping the Long Earth - but in turn, the Long Earth is shaping mankind, and Joshua, now a married man, must deal with a crisis that threatens to plunge the Long Earth into a war unlike any that have come before. This is another thoroughly engrossing and inventive novel from two giants of science fiction.