A Wind in the Door by Madeleine L'Engle

This is another case of "I know I read it, but I just don't know when or anything about it." The only solid memory I have of it is of the description of the cherubim, Proginoskes. I remembered something about a big ball of wings and eyes and it might have in fact been an illustration.

A Wind in the Door picks up about a year after the events of A Wrinkle in Time. Meg is in high school and Charles Wallace has started with school. Charles Wallace is, in fact, having as much trouble adjusting to school as Meg did. He's super smart and tiny; it makes him a target for bullying.

Charles Wallace is also suffering from some sort of vague illness. When he greets Meg with a story about dragons in the garden, even Meg gets concerned. If the bullying wasn't enough, now her cherished little brother is seeing things. Nevertheless, she goes to check it out and finds, not a pack of dragons, but rather a single cherubim and a monolithic teacher.

In the larger world, something is causing the stars to disappear. Of course it is all connected and Meg and Calvin must race time to save Charles Wallace.

If A Wrinkle in Time was underpinned with physics, A Wind in the Door is exploring cellular biology. Most of the action has to do with mitochondria which really are quite interesting. Every cell in our body has them and mitochondria have distinct DNA from our own. They are symbiotic prokaryotes which was a new idea at the time that the book was written. The science is a little messed up, but we really do need mitochondria for our cells to function so it's pretty cool stuff.

There is also a stronger religious theme floating through this one probably because of the cherubim. I didn't find it obnoxious, but it was definitely more present.