The museum as a magical building full of all the interesting things that have been locked away was fun, and overall this is well-written mid-grade fiction. The anti child protective services message, however, was hammered at again and again, too blunt to be pleasant. I think it's trying to be about helicopter parenting, and why that's a bad idea, but the "Gaurdians," who can take children into "care," a terrible orphanage where the children are chained to their beds, become the primary antagonists, not the overprotective parents. I'm not at all sure I love a book that is expressly about fear mongering surrounding social work and child protective services.

Mind. Blown. I don't think it's too much of a spoiler to say that this will make you want to reread all the other books to see if you can spot the things mentioned in this one.

As a stand-alone it would really only be a 3 star novel, but as the cap to a saga that manages to bring new pieces to the universe and make it all fit beautifully, it's solidly a 4 star.

The characters have no motivation or inner lives, and the alien life-forms seem to exist only so that our characters can kill them. Frankly, I identify more with the poor aliens than with the precious prince with mommy issues.