Burning Up (Berkley Sensation) -  'Meljean Brook',  'Virginia Kantra', 'Angela Knight', Nalini Singh
I bought the book so I could read the prequel to "The Iron Duke" and decide if I wanted to read that. So okay, that's going the long way round, but it works for me. And "Here There Be Monsters" worked too. The world building was seriously wow.

The surprise was how much I enjoyed Nalini Singh's psy-changeling story. Previously I'd read a contemporary romance by her and enjoyed it, but my one attempt at her angels series put me off. But I enjoyed the psy-changeling story in Burning Up sufficiently that I'm now reading "Slave to Sensation", the first in the series.