The pace of the book continues to accelerate as one nears its end. Indeed, more happens in the last two chapters than in the first four. Best of all, there are no loose ends.
Remember Harry hearing voices that no one else could hear? He also speaks a language very few people can speak: Parseltongue. This leads Hermione to suspect that the creature freezing/stiffening people around school is a snake.
However, Hermione herself is frozen/stiffened, and Ron and Harry have no idea what do regarding the attacks at school. They visit her in the school's hospital ward, and find a note that she had written, which contains information leading them to the Chamber of Secrets.
A lot happens in a short time, but here's some things to consider regarding the big picture:
1) This child's book is a fresh addition to youth literature because unlike the books I read when I was 11 or 12, this one fits neatly between Morality Tales for Eight Year Olds and Horrific Stories Involving Murder for Sixteen Year Olds. Around age 11, I found books geared for people my age to fall into one of the two categories above. There was classic literature, but those books are invariably about some time before the present. Harry is, for the moment, close enough to the present in terms of speech and mannerisms to not be a distraction.
2) Harry and his friend break so many rules, in the context of their own school, that they fear expulsion much of the time. This is realistic, and the fact that the adults in the story are aware of it, disapprove, but realize the situation that they were in, is encouraging. Rules are not absolute.
3) A fascinating, almost science fiction concept is included in this story, that of the diary of Tom Riddle. Riddle was a student at Hogwarts many decades earlier, and wrote a diary that preserved him as "a memory". Essentially, a kind of mind uploading, and the diary possesses a form of artificial intelligence. I say "kind of" and "form of" because this is a story about magic, not technology.
4) Finally, Tom Riddle, in his fight against Harry, near the end, channels a stereotypical villain from a James Bond movie. "Hello, Harry. Welcome to my secret lair. Let me tell you my story, my methods and techniques, my plans for the future, and all details contained therein, and attempt to kill you unsuccessfully."
Overall, this second Harry book is better than the first, and I'm actually looking forward to it.
The current book I'm reading is neither military history, nor fantasy. It is The Mystery of Capital, by Hernando de Soto.