I was mildly disappointed when I opened The Long War by Terry Pratchett and Stephen Baxter, since the first book in this series, The Long Earth, ended on something of a cliffhanger. Thus, when book 2 opened 20 years after the events of book 1, I was mildly annoyed.
That annoyance didn't last terribly long as the plot got rolling along. Once again, most of the focus is on Joshua, an orphan and natural stepper currently living in Hell-Knows-Where on Earth West 1 million or so. He has a wife and kids now (the wife being the one whose journals narrated part of book 1, talking about how settlement of the Long Earth progressed), and serves as mayor of his town. Then Sally (another natural stepper, but one who can sense the "soft spaces", places where one can get between multiple Earths at a go) re-enters his life, begging him to go back to Datum Earth to do what he can about the mistreatment of the Trolls.
(For those of you who have not read the first book, here's a quick setting synopsis. On step day, plans for steppers popped out on the internet via Sally's father. Made of cardboard and a potato to power it, one could hit the switch and "step" East or West onto a parallel Earth. Or several steps, really. Josh and Lobsang [Lobsang being an AI who thinks he is the reincarnation of a Tibetan motorcycle repairman] took a special airship West across the Long Earth to see what they could find. Along the way, they found races that could also "step", most of which had not ever really been seen on "Datum Earth". One such race was the trolls, who have a group intelligence and communicate in song. Another, Elves, were bloodthirsty hunters.)
Josh's wife, Helen, is fighting with her dad, who lives a few steps away in Valhalla, which is currently involved in a dispute with Datum Earth over the so called Aegis laws. Which basically state anyone living in an alternate Earth in what would be current US political boundaries (Most of the Earths retain similar shape, but there are "jokers" and a few worlds where the Earth no longer exists) must submit to US regulations. Folks in far out Earths like Valhalla feel that they're being taxed without representation. Which leads to the trip of the USS Benjamin Franklin across the worlds to remind settlements that they are still United States citizens. What that crew finds between poles of Datum DC and Valhalla is a mushy middle ground where they have to step in to help solves strange disputes in various colonies. We also have a Chinese expedition going East to Earth East 6 Million, wherein we see another theme of the novel... One of the worlds they pass is habitated by non-human sapient creatures about to be wiped out by a typhoon. That the crew does nothing to help them causes a very reserved girl from Valhalla to finally find her humanity.
We also have trolls vanishing about halfway through, which makes the last half a race between Josh and Sally to figure out who can find the trolls first.
I enjoyed this book, and indeed, I've enjoyed the series so far. And this one was an improvement, since there weren't near as many plot threads in play. There's still quite a bit going on, but the narrative is much more cohesive in book 2.