2013 YA gaslamp fantasy, first of a pair though it stands alone.
Emilie is fleeing from her guardians when she stows away on the wrong
ship, and finds herself part of an expedition to the world within the
world…
Although this is not the same world as Ile-Rien, I got a similar
feeling from the setting: roughly turn of the 20th century technology,
steam ships and gas lamps. Wells writes as someone who has met, and
smelled, this kind of machinery. Meanwhile there's magic, but only a
few people can do it, so it's not common enough to be a part of
society.
But also this is in the tradition of lost worlds and subterranean
fiction specifically, from that transitional period when it had
grudgingly to be accepted that explorers had reached or at least seen
most places, but just maybe there might still be a hidden valley or
a deep cave that would let you find true wonders.
The inner world is populated, of course, and by people (if not humans)
who have their own plans, to which the addition even of a civilian
ship may make a substantial difference. Our heroes are looking for a
previous expedition that became stranded, and there's a rival
gentleman-adventurer out there somewhere… It's clearly a little hard
to justify Emilie's acceptance by the leaders, but she turns up while
they're rather busy with other things and promptly makes herself
useful, which helps a great deal.
Of course this is still Martha Wells, so it's not just daring
escapes and cunning plans; there's real consideration of cultural
friction and indeed how to be an adventuress without entirely losing
one's reputation. But this is mostly a light and cheerful book and I
rather enjoyed it.