A followup to the excellent alternate history, The Explosionist—which was a Tiptree Honor book a couple of years ago. I loved the first book (it's partially set in Scotland which warmed this cold heart!) and have been looking forward to this one since. Invisible Things takes up a little after the first—and could probably be enjoyed without reading the previous one—with 16 y.o. Sophie living in Denmark at Niels Bohr's Institute for Theoretical Physics. With the threat of war rising, she goes from there to the frozen north and meets the Snow Queen herself—an arms dealer who also knew her deceased parents and may know more about how they died. I'm not sure if there will be a third book, hope so, but in the meantime this was a very quick, quite different read.