2014 YA gaslamp fantasy, second of a pair though it stands alone. No
sooner is Emilie back from the hollow world than something strange is
spotted in the sky…
Something is coming through a conjunction of aether currents, and
to find out more about what it is will take an expedition by airship.
Soon enough, Emilie, the Marlendes and others are on their way again.
There are echoes of the previous book here; once more, there's a
missing earlier expedition to the same place, and thinking opposition
as well as natural hazards. But rather than the indigenous
civilisations of the Hollow World, here we get some extremely alien
aliens (I speculate without evidence that after doing that Star Wars
book Wells fancied writing about an alien species that it would be
entirely impractical to portray on film). In the grand tradition of
At the Mountains of Madness, these are people, even if they are
thoroughly not human to the point that communication is a challenge in
itself.
There's more built environment this time round, but also some alien
landscape, and I found this book altogether satisfying—not least
because these are proper Wells characters: not simply Good or Bad, but
with their own troubles and weak points, neither angels nor demons.
but people trying to act for the best as they see it
There haven't been any more books in the series, though the possibility
is there.