The Last Hour Between Worlds by Melissa Caruso

In the Deep Echoes, no one can save you.

Star investigator Kembral Thorne has a few hours away from her newborn, and she just wants to relax and enjoy the year-turning party. But when people start dropping dead, she’s got to get to work. Especially when she finds that mysterious forces are plunging the whole party down through layers of reality and into nightmare.

One layer down: It’s no big deal. Stay alert, and you’ll be fine.

Two, three layers down: Natural laws are negotiable, and things get very strange.

Four layers down: There are creatures with eyes in their teeth and walls that drip blood. Most people who fall this far never return.

Luckily, Kem isn’t most people. But as cosmic powers align and the hour grows late, she’ll have to work with her awfully compelling nemesis, notorious cat burglar Rika Nonesuch, for a chance to save her city—though not her night off.