There are all kinds of things the public doesn't need to know about. Ancient technology, magical tomes, mad scientists' creations, and other things that just don't fit into the way we want the world to work. The White Boxes were set up to contain these objects until people are more ready to deal with them, and to make sure that monster hunters have access to the resources they need to face any new threats.
A previous collection of short stories, Unboxed, detailed some White Boxes and the things that can be found there. But this novel features an Ensemble Cast dealing with a threat to the White Boxes themselves.
Possibly Reference Overdosed; though the author still has no idea if anyone will spot most of them. Among other things, there are several chapters that share titles with books written by the author's friends.