Over the Woodward Wall is the first in the Up-and-Under series by by A. Deborah Baker, which is a pen name for Seanan McGuire, whose October Daye series I’ve read and really liked. And it’s free right now in the US.
Free (for now) at Kindle US | Kobo US
And the second book in the series, Along the Saltwise Sea, is on sale right now for $2.99, which is a nice price drop from its normal $7.99. And at least in the October Daye series, Baker/McGuire’s books don’t go on sale very often. So I may grab this one on spec, assuming I’ll like the first…